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ELEMENTARY 
CONCRETE CONSTRUCTION 



Elementary 
Concrete Construction 



LEON H. BAXTER 

Supervisor of Manual Training 
St. Johnsbury, Vt. 




The Bruce Publishing Company 

MILWAUKEE, WISCONSIN 






Copyright 1921 
The Bruce Publishing Company 



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AUG 22 192! 

©CI.A622489 



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Introductory Note 

It affords me great pleasure to commend "Elementary Concrete 
Construction" to teachers, parents and all others interested in 
the education of boys. My confidence is based upon personal 
knowledge of Mr. Baxter's aims and methods. During the six years 
that I was Superintendent of Schools in St. Johnsbury I had ample 
opportunity to see the interest which these projects aroused in the 
boys, and their reaction upon the home and community. 

Pedagogically, Mr. Baxter's work is the best exemplification of the 
project method that has come to my notice. The reasons for this soon 
become obvious. The boy chooses the project, or problem, which 
appeals to him, does his work with a minimum of supervision, puts 
forth his best effort, and takes pride in the quality of his workman- 
ship. He thus experiences the joy of real achievement. 

The practical application of elementary work in concrete has been 
repeatedly demonstrated by Mr. Baxter. Under his direction the boys 
of the manual training department were engaged by the school board 
to do repair work during vacations, such as laying basement floors, 
w r alks, steps, setting posts and flag poles in concrete in and about the 
school buildings. They also did work for individuals and societies, 
as well as around their own homes. We are pleased to add that their 
work stood the test of time. 

Any book containing projects which arouses the enthusiasm of 
the boy, holds his interest, and inspires him to think and to do, is 
bound to have a wide sphere of usefulness. 

WALTER H. YOUNG, A. M.. 
Superintendent of Schools, 

Somersworth, N. H. 



Author's Preface 

Knowing the scarcity of material, of an elementary nature, on 
the subject of concrete construction, the author has gathered together 
a series of problems in concrete work, which, with but a very few 
exceptions, have all been successfully worked out by pupils in the 
seventh and eighth grades. 

This book is to all intents and purposes a condensed textbook on 
those things which are necessary to follow, in order to make con- 
structive work in concrete a success. 

The excessive cost of lumber, together with its scarcity, has 
brought home very convincingly the necessity of finding some material 
which should be as good or better, as a substitute. 

Concrete fulfills all the requirements of such a material. He who 
uses this medium builds for permanence and the many uses to which 
it may be put make it the ideal constructive material. 

It is correlated with woodworking in an excellent manner in the 
making of forms, and its possibilities are such that the user has a 
wide field for original design. 

The author owes his sincere thanks to the Association of Ameri- 
can Portland Cement Manufacturers, the Atlas Portland Cement Com- 
pany and the Alpha Portland Cement Company, for data and photo- 
graphs loaned and information given by them. 

All photographs of the boys at work and those showing the com- 
pleted projects were taken by the author. 

Thousands of feet of concrete have been laid, under the supervision 
of the writer, by boys whose ages ranged from ten to fourteen. 

Hundreds of dollars have been saved by the school department 
by the work done by these boys. The boys received pay for their 
work, learned to know and handle concrete and were taught, through 
this, the dignity of labor. 
St. Johnsbury, Vt. LEON H. BAXTER. 

Jan. 12, 1921. 






TABLE OF CONTENTS 

Page 

History of Cement 7 

Composition of Cement 7 

Classes of Cement 8 

The Manufacture of Portland Cement 8 

Quarrying 8 

Drying and Grinding • • 8 

Proportioning and Mixing 9 

Burning to Incipient Fusion • 9 

Grinding the Clinker and Adding Gypsum 9 

Commercial Cement and Its Storage 9 

Aggregates • • 10 

Value of Different Rocks 10 

Fine Aggregate — Sand 11 

Tests for Loam • 11 

Method of Washing Sand 11-2 

Coarse Aggregate — Gravel 11 

Cinders as Aggregate 13 

Water . . 13 

Proportioning the Materials 13 

Various Mixtures for Various Purposes 15 

Equipment Used in Elementary Concrete Work 15-7 

Mixing 17 

Quantity of Materials and Sizes of Measuring Box 17 

Placing Concrete 19 

Reinforcing 19 

The True Use of the Word Cement 21 

Protection of Concrete 21 

Forms for Concrete • • 21 

Length of Time Forms Should Be Left in Place 21 

Various Surface Finishes for Concrete — Mortar Finish 22 

Brush Surfaces • • 23 

Rubbed Surfaces 23 

Dressed Surfaces • • -24 

Colored Surfaces 24 

Design 25 

Waterproofing Concrete 25 

The Use of Concrete in Winter 26 

Estimating . . . . 26 

Table for Determining the Quantities of Materials Needed 27 

Mortar and Concrete Mixtures 28 

Questions and Answers 29 

PART II 

PROBLEMS 

A Concrete Brick ■. 32-3 

Anchor Weight 34-5 

Miscellaneous Problems 36-7 

Concrete Roller 38-9 



TABLE OF CONTENTS— Concluded 

Page 

Horse Block 40-1 

Concrete Dish for Bulbs 42-3 

Flower Boxes 43-5 

Concrete Hitching Post 46-7 

Concrete Fence Posts ••.... 48-9 

Concrete Supports for Parallel Bars 50-1 

Concrete Sand Box 52-3 

Lawn Pedestals • 54-6 

Sun-Dials 54-6 

Setting of the Sun-Dial 57 

Concrete Garden Bench 57-9 

Concrete Troughs • 57-60 

Small Concrete Watering Trough 61-3 

Circular Watering Trough 61-4 

Waste Water Receptacle 64-5 

Concrete Steps and Porch Construction 66-7 

Concrete Walks 68-75 

Two Course Curb and Gutter 68-74 

One Course Curb and Gutter . . . • • 74-7 

Feeding Floors for Hogs and Cattle 76-8 

Carriage and Automobile Washing Floors 76-9 

A Concrete Manure Pit 79-80 

Concrete Duck Pond or Wading Pool • • 82 

Hot Beds and Cold Frames 82-3 

Laying Out Foundations • • 84-5 

Simple Foundations 86-7 

Various Types of Foundations • • 88-9 

Retaining Wall 91-2 

Design for Small Dam • • 91-2 

Design for Concrete Fountain 94-5 

Concrete Bird Bath • • . 96-7 

Single Concrete Garage 98-9 

Details of Wall and Window Construction — Wall Reinforcing 100-1 

Corner Reinforcing • • 101 

Window and Door Openings 101 



Elementary Concrete Construction 

PART I 

History of Cement 

There is an old saying, "There is nothing new under the sun." 
This holds true regarding the history of cement. To many the use of 
cement is of recent origin, the result of modern methods of construc- 
tion. Nothing is further from the truth. With the dawn of civiliza- 
tion came the use of cement. Ancient Egypt and Assyria contributed 
wonderful examples of its use, one notable instance being the Queen's 
Chamber in the Great Pyramid. The Appian Way and the Pantheon 
at Rome, together with her aqueducts, are other examples of concrete 
art, some of which are in actual use at the present day. 

From the time of the Romans until about 1756, little was done in 
the manufacture of cement. In 1824, Joseph Aspdin, of Leeds, Eng- 
land, discovered the method of making cement and named it "Portland 
Cement" from the fancied, though really slight, resemblance to the 
noted oolitic limestone, which by the w r ay is used in the London West- 
minster Cathedral, found on the Isle of Portland, on the south coast 
of England. 

Although European countries began manufacturing cement at 
once it was not until about 1850 that its commercial success was as- 
sured. In 1818 natural cement was discovered in New York State by 
a man named White, an engineer on the Erie Canal. 

The first American mill was built at Rosendale, N. Y., and from 
this fact obtained the name of "Rosendale Cement." The first artir 
ficial or true cement was not manufactured until 1875, and it was not 
until 1896 that the annual production reached the million barrel mark. 
Previous to this time the English and German cements were regarded 
as having the greatest strength. 

The growth of this important industry has increased wonderfully 
and today individual firms are turning out over 9,000,000 barrels 
yearly, and preliminary figures for 1919 show that the annual produc- 
tion for the United States will be in excess of 80,000,000 barrels. 
Pennsylvania is the banner state in production of cement, producing 
over 28,000,000 barrels yearly, or nearly three times as much as her 
nearest competitor, Indiana. 

Composition of Cement 

Cement is substantially an artificial stone made by uniting in very 
exact proportions, two materials, one of them a rock-like limestone, 
or a softer material like chalk, which is nearly pure lime, with a ma- 
terial like shale, which is hardened clay. 

7 



8 ELEMENTARY CONCRETE CONSTRUCTION 

Classes of Cement 

The method of manufacture determines the three classes into 
which cement is generally divided. These processes are: 1, the dry 
process ; 2, the semi-wet process, and 3, the wet process. 

In the dry process the raw materials are ground, mixed and burned 
in their original dry state. The wet process consists of mixing the 
raw materials, of grinding them with water and of feeding them into 
large rotary kilns in the shape of a "slurry" containing enough water 
to make the whole mass of a fluid consistency. The semi-wet process 
resembles the wet process except that the slurry contains compara- 
tively little moisture. 

The Manufacture of Portland Cement 

The manufacture of Portland cement itself is divided into five heads 
as follows : 

1. Mining and quarrying of raw material. 

2. Drying and grinding. 

3. Proportioning and mixing. 

4. Burning the two materials to incipient fusion. 

5. Grinding the clinker thus burned to an extremely fine powder, 
meanwhile adding the proper proportion of gypsum, the resulting 
powder being known as Portland cement. 

Quarrying 

The excavation of the raw materials is the first step, and this is 
done by one of three general methods. First, quarrying and digging 
from open pits. Second, mining from underground workings. Third, 
dredging from deposits covered by water. 

The usual method of quarrying the rocks is similar to that followed 
in all quarry operations. The rock is dislodged from the quarry face 
by means of an explosive and then dumped into side dump cars or 
aerial trams by either steam shovel or manual labor, preferably the 
former. The stone is then conveyed to the stone house, where it is 
crushed to comparatively small sizes and then transported to storage 
bins before being mixed with other ingredients. While in storage 
the stone may be sampled and analyzed. 

Drying and Grinding 

One method of grinding, before being placed in the storage bins, 
is to pass the limestone, shale, or cement rock through crushers and 
ball mills, or other preliminary grinders, from which it is conveyed to 
storage bins. The ball mills are cylindrical steel drums containing a 
quantity of steel balls. The material to be ground after drying, is con- 
tinuously added. 

As the cylinder rotates the balls roll, thus grinding the rocks to 
coarse grit. The coarse grits are then run into storage bins. Tube 



PROPORTIONING AND MIXING 9 

mills which are used further on in the process are similar in general 
to the ball mills. 

Proportioning and Mixing 

After the raw materials have been drawn from their respective 
bins and accurately proportioned by weighing they are delivered to 
a screw conveyor which completes the mixing and delivers the com- 
bined material to the tube mills. 

The tube mills are revolving cylinders half full of flint pebbles or 
steel slugs which reduce the material continually being fed, into prac- 
tically the fineness of finished cement. At this point we are, however, 
a long way from the finished product. 

All the tube mills deliver to the same conveyor, which results in 
a uniform product of the raw material mill as a whole. 

Burning to Incipient Fusion 

From the tube mills the material is fed into kilns by a system of 
conveyors. The kilns are from 6 to 8 ft. in diameter and average 
about 125 ft. in length. They are lined with fire brick, and revolve 
at the rate of one revolution a minute and it is estimated that it takes 
about one hour for one lot of material to pass through. Powdered 
soft coal, crude oil, or gas is used as fuel, powdered coal being most 
commonly used. It is blown into the kiln at the end opposite that at 
which the raw material enters. 

The raw material entering as a powder is gradually brought to 
the point of incipient fusion at a temperature of 2500° to 3200° 
fahrenheit, producing clinkers varying in size from y^ in. up to \y 2 in. 
in diameter. 

The clinker is red hot when discharged, but is quickly cooled by 
sprays of water or cold air blasts which are played over the elevator 
and also upon the clinker when delivered to the storage pile. 

Grinding the Clinker and Adding Gypsum 
From the kiln the clinker may go either to the clinker storage pile 
or directly to the grinding department. Before sending to the tube 
mills for the final grinding gypsum is added either by hand or auto- 
matically. This material is added to prevent the cement from setting 
too quickly. Otherwise the cement would harden quickly and develop 
but little strength. The tube mills grind the clinker so fine that the 
particles are less than 1/200 in. in size. It is now placed in storage to 
season. 

Commercial Cement and Its Storage 

Cement is placed on the market in bags weighing 94 lbs. net and 

barrels of 376 lbs. net, four bags to the barrel. Cement must be stored 

in a dry place, for dampness is the one element fatal to its keeping 

quality. Dampness causes the cement to become lumpy and even to 



10 



ELEMENTARY CONCRETE CONSTRUCTION 



solidify throughout and as a result absolutely unfits it for use. Lumps 
which do not crumble at the slightest touch should be thrown out. 
Place the cement on a wooden platform raised several inches from 
the ground. Never store directly on a concrete floor. Plate 1 shows 
the proper method of storing. 

Aggregates 

As a chain is no stronger than its weakest link, so concrete is no 
stronger than the weakest element of which it is composed. 




r/o. / 

Tfl£ FftOPER WAY TO 
5TOf?£ CEfY/TfYT 

PLATE I 

The material entering into the composition of concrete, such as 
sand and gravel, are called aggregates, sand being the fine and gravel 
the coarse aggregate. If good results are to be obtained extreme care 
should be taken in selecting these. They should be clean, hard, coarse, 
and well graded ; clean, so that the coating of cement may adhere 
directly to the particles ; coarse, because coarse aggregate is more 
easily covered with cement than a fine one ; hard, so that it may retain 
its form under pressure. 

Value of Different Rocks 
Comparative tests have proven that in the order of their value for 
concrete, the different materials stand approximately as follows : 



FINE AND COARSE AGGREGATES 11 

1. Granite. 

2. Trap Rock. 

3. Gravel. 

4. .Marble. 

5. Limestone. 

6. Slag. 

7. Sandstone. 

Fine Aggregate — Sand 

Aggregate passing through a sieve of *4 m - rnesh is called sand. 
It should be sharp and free of all vegetable matter. The size of the 
grains should be graded from coarse to fine, the coarser particles 
predominating. 

Tests for Loam 

Sand should be free from loam or vegetable matter. A fair test 
for quality of sand is as follows : Take two handfuls of moist sand, 
and holding the palms about y 2 in. apart let the sand run through. 
Repeat this several times and then rub palms lightly together to 
remove fine grains. Examine to see if a fine, sticky film adheres to 
the palms ; if so, do not use it as it contains loam. Fine roots also 
indicate vegetable matter. 

Another test is to fill a fruit jar to the depth of 4 in. with sand. 
Fill with water to within 1 in. of the top. Shake well and allow to 
stand for two hours. Sand will sink to the bottom while any mud 
or clay will settle on the top of the sand. If more than *4 in. of such 
deposit remains, it is not suitable for use without washing. 

Method of Washing Sand 

Washing sand by wetting the pile with a hose is wrong — it only 
transfers the dirt to the lower part of the pile. 

The proper way is for one man to shovel it on the upper end of a 
trough, like the one shown in Plate 2, while another man washes it 
down the incline by pouring water on it. There is a fine screen (size 
of mosquito netting) cleated to the incline. When the sand and 
water come to this screen, the dirty water drains through and leaves 
the clean sand ready for use. 

Coarse Aggregate — Gravel 
This should be clean and hard. The best results are obtained by a 
mixture graded from small to large, as it forms a more compact mass 
freer of voids. 

The crushed rock should be screened on a *4 m - screen to remove 
the fine particles, or sand. 

As a general rule the ordinary run of bank gravel is not suitable for 
use without sifting and remixing, as described later. This is because 
there is generally too much sand for the gravel. 



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CINDERS AS AGGREGATE 13 

It is not well to use pebbles or pieces of broken stone if their great- 
est dimension is more than one-half the thickness of the concrete you 
are placing. 

Cinders as Aggregate 

Cinders are used to some extent as a substitute for crushed stone 
or gravel. They are lighter and more porous than stone but less 
strong, but where lightness is more important than strength or where 
a poor conductor of heat or sound is required, they may be used. 

Successive floors of tall buildings are often laid with cinder con- 
crete. Roofs are also constructed with it. It cuts more easily than 
that made of stone and nails may be driven into it. Cinders used in 
concrete work should be practically free of ashes. Wood ashes should 
never be used. 

Power plant cinders are better than those from household fur- 
naces as the intense heat of the former fuses most of the ash into 
hard material. It should be drenched with water to wash out the 
finer material. Concrete made of cinders should not be rammed, as 
the material will break up easily. As cinders have been subjected to a 
great heat they are good from a fireproof point of view. 

Water 

Use nothing but clean water. Scummy, dirty, muddy or alkaline 
water must not be used. A good drinking water is always right to 
use for mixing concrete. The amount of water to be used varies with 
the material used and results desired. 

Cold water (below 40° fahrenheit) retards the set of concrete. The 
amount of water used varies with conditions, as before stated, and di- 
vides green concrete into three groups according to its consistency, 
"wet," "medium" and "dry." 

Wet concrete requires but little puddling, flowing readily into 
corners and crevices. It is preferred for reinforced concrete as the 
metal can be easily imbedded. "Wet" concrete requires a bucket or 
similar vessel for handling. 

For general work "medium" concrete gives the densest, hence the 
strongest mixture. It quakes like jelly and can be carried on a shovel. 

"Dry" concrete should contain enough water so that tamping 
brings it easily to the surface. 

Proportioning the Materials 

By "proportioning" we mean determining the necessary quantities 
of cement, sand and gravel, for a piece of work. 

Cement is always the smallest quantity in a mixture and is always 
mentioned first. A bag of cement contains approximately 1 cu. ft., 
so that amount of cement is taken as the unit of measure. 

The second figure is always- the number of parts of sand. The 
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VARIOUS MIXTURES 15 

third figure is the number of parts of stone or gravel. Thus when we 
speak of a 1-2-4 mixture, we mean that to every cubic foot (bag - ) of 
cement there are 2 cu. ft. of sand and 4 cu. ft. of gravel or stone. Sat- 
isfactory results can only be obtained by proper proportioning. 

The object of proportioning- is to make a sufficiently dense concrete 
mixture. Sand or gravel or crushed stone, alone, have between their 
particles empty spaces called "voids." To make dense concrete the 
cement, sand and stone must be proportioned so that the voids in the 
coarse aggregate are filled with the finer particles of sand and cement, 
and so that the voids in the sand are filled and bound together with 
particles of cement. If this subject of voids is borne in mind, you will 
not make the common mistake of estimating that 1 cu. ft. of cement, 
2 cu. ft. of sand and 4 cu. ft. of stone will make 7 cu. ft. of con- 
crete. On account of so much of the material being used in filling up 
voids, the actual total quantity of concrete obtained by mixing these 
quantities of aggregates is only a little more than the quantity of 
stone — 4 cu. ft. — see Plate 3. 

For almost all work twice as much coarse aggregate (gravel or 
stone) must be used as fine aggreg-ate (sand). 

Various Mixtures for Various Purposes 

A mixture of 1 part cement, \V 2 parts sand and 3 parts coarse 
aggregate is suitable for roads, columns, waterproof buildings and 
other constructions coming under high stresses. Such a mixture is 
termed a rich mixture. 

A mixture of 1 part cement, 2 parts sand and 4 parts coarse aggre- 
gate is suitable for roofs, arches, reinforced floors, columns, reinforced 
engine bases subject to considerable vibration, beams, tanks, extra 
strong walls, sewers and various other work requiring watertightness. 
This mixture is termed a standard mixture. 

A mixture of 1 part of cement, 2 l / 2 parts sand and 5 parts coarse 
aggregate is suitable for retaining walls, ordinary floors, ordinary 
machine foundations, abutments, sidewalks, piers, and sewers requir- 
ing extra heavy walls. Such a mixture is known as a medium mixture. 

A mixture of 1 part of cement, 3 parts sand, and 6 parts coarse ag- 
gregate is suitable for foundations supporting stationary loads, unim- 
portant work in masses, backing for stone masonry and heavy walls. 
It is known as a lean mixture. 

Equipment Used in Elementary Concrete Work 

Plate 4 shows all necessary concrete equipment for hand mixing, 

much of which can be of home made construction : 2 good quality 

No. 2 square nosed "paddy" shovels ; 1 or more tampers of about 20 

lbs. weight, as shown ; a home made wooden float or trowel of di- 



16 




MIXING 



17 




Illus. 1. A Typical School Outfit. 

mensions shown on drawing ; a clean water barrel, one which has not 
previously contained oil ; 2 galvanized iron water pails ; a heavy gar- 
den rake ; 1 galvanized sprinkling can of fairly good size ; some 
garden hose ; 1 sand screen made of ^4 i n - wire mesh ; 1 measuring 
box or frame (see drawing) ; 1 mixing platform ; 1 strong metal 
wheelbarrow; trowels; a carpenter's level; 1 tool for edging and 
1 for jointing. 

Illus. 1 is a photograph showing the typical school outfit. 

Mixing 

After proper sand and gravel have been secured, the success or 
failure of the finished job is in the proper mixing. 

Have all gravel and other material placed convenient to the work. 
A good amount of sand should be sifted previous to the mixing and 
the method is clearly shown in Illus. 2. The use of the measuring box 
is of great assistance and a table showing the depths, widths and 
lengths for various mixes is given below. 

Illus. 3 shows the measuring box in use-. 

Quantity of Materials and Sizes of Measuring Box 





Cement 






Concrete 


Size of Measuring Box 


Mix 


(bags) 


Sand 


Gravel 


made, 
(cu. ft.) 


Length Depth Width 


l-lVa-3 


2 


2.8 cu. ft. 
or % bbl. 


5.7 cu. ft. 
or 1V> bbl. 


7.0 


3' 0" x 2' 0" x 10" 


1-2-4 


2 


3.8 cu. ft. 
or 1 bbl. 


7.6 cu. ft. 
or 2 bbl. 


9.0 


4' 0" x 2' 4" x 10" 


l-2V 2 -5 


2 


4.8 cu. ft. 
or 1% bbl. 


9.5 cu. ft. 
or 2 y 2 bbl. 


10.9 


4' 6" x 2' 2" x 12" 


1-3-6 


2 


5.7 cu. ft. 
or IV, bbl. 


11.4 cu. ft. 
or 3 bbl. 


12.8 


4' 6" x 2' 7" x 12" 



INSIDE DIMENSIONS 
(Note. — A cement barrel holds 3.8 cu. ft.). 



18 



ELEMENTARY CONCRETE CCNSTRUCTICN 



For a 1-2-4 mix, which 
is an average mix, the box 
shown in Plate 4 is the 
proper size. This is filled 
half full of sand and emp- 
tied on the mixing board 
and two bags of cement are 
opened and spread upon it. 
Turn the dry sand over and 
over with a shovel until it 
is thoroughly mixed and of 
a uniform color. See that 
there are no hard lumps or 
cement "pockets" remaining. Spread out the mixture and empty on 
it the mixing box filled even full of gravel. Mix this thoroughly. 

Add three-quarters of the required amount of water — say, about 
Y\ gallon to each cubic foot of concrete. Apply the water with a 
sprinkling can or hose with a spray nozzle, slowly and evenly, mixing 
the whole mass at the same time. 

Illus. 4 and 5 show the method of applying the Avater and Illus. 6 
the method of mixing. 




Illus. 



Sifting Sand Before Mixing. 



Sa 


1 


1 


mm 




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Illus. 3. Measuring Box in Use. 



PLACING CONCRETE 



19 




■ 



Add more water when dry 
spots appear until the whole 
mass has been turned over at 
least three or four times. The 
mixture should now be sho- 
veled into a compact mass 
to wheel away. 

It is extremely bad practice 
to apply water with a hose 
which has not a spray attach- 
ment as the heavy stream will 
cause the cement to wash away 
and be deposited unevenly 
throughout the mixture. 

Placing Concrete 

After the concrete has been 
mixed, it is in plastic form and 
must be placed in forms or 
moulds to shape it in the re- 
quired form. The subject of 



lllus. 4. Applying Water to Mixture. 

forms for concrete will be taken up later on. 

Concrete must be placed as soon as it is thoroughly mixed as it 
begins to set very quickly. 

Methods of placing vary with working conditions and the nature 
of the construction, but the following are useful rules for nearly every 
sort of work : 

A. Place concrete in layers about 6 in. thick. 

B. Pack it down lightly with a tamper or rammer (see Plate 4), 
until water shows on top. This makes the mixture dense. 

C. If a smooth surface is desired, such as on an exposed wall, 
work a spade back and forth and up and down between the concrete 
and the form on the side which will be exposed to view. 

This brings the coating of mortar next to the form. Where a 
spade cannot be used substitute a thin wooden paddle, made from a 
board 1 in. by 4 in., sharpened to a chisel edge on one side of the end. 
Keep the flat side of the paddle next to the form with the sharpened 
side turned in. 

The dryer the mixture the more important the tamping and spading. 

Reinforcing 

Where any great strength is required reinforcing should be used. 

A concrete column, for instance, will support a tremendous load, 
but a side or lateral pressure of half the magnitude might cause the 
same column to fall. Concrete when reinforced with steel rods, wire 



20 



ELEMENTARY CONCRETE CONSTRUCTION 




Il'ius. 5. Applying Water with Sprinkling Can. 
Illus. 6. Method of Mixing. 

strands, or wire mesh, has added strength and will stand considerable 
tension. Steel is elastic and when properly used with concrete imparts 
sufficient of this elasticity to make an ideal building- material. 

Where a large amount of reinforcing on heavy work is required 
rods should be used. For flat work requiring less strength, wire 
mesh or in some cases any kind of wire is suitable. 

An invariable rule in placing reinforcing- is to insert where the 
pull will come. Thus in a beam or slab it is close to the bottom, 
while in a wall built to withstand earth pressure it is placed in the 
face nearest the earth. 






TRUE USE OF WORD CEMENT 21 

The True Use of the Word Cement 

It is well to say a word here regarding" the use of the words "ce- 
ment" and "concrete" as they should be spoken. We often read and 
hear of cement walks, cement houses, cement steps, etc. This is ex- 
tremely incorrect ; the proper word to use is "concrete." There never 
can be such a thing as a cement house, etc. It must be remembered 
that cement is but a powder and bears the same relation to concrete 
that flour does to bread, and is only a part of the finished product. 

Protection of Concrete 

If the forms are removed as soon as the green concrete will sus- 
tain itself, where the surface is exposed to the elements, it should be 
protected from the drying action of the sun and hot winds. 

Concrete should set 5 or 6 days before being exposed and during 
this interval it should be sprinkled with water morning and night to 
keep the surface of the concrete from drying out faster than the 
interior. 

Protect exposed vertical surfaces with old burlap, hung 1 in. or 
so from the surface, and keep this cover moist all the time. 

Flat surfaces such as feeding floor and walks should be protected 
from rain, sun, wind and frost by sand, straw or building paper. 

Forms for Concrete 

Plastic concrete is very heavy and forms therefore should be 
strongly made. Green lumber should be used, as dry, seasoned ma- 
terial will swell and warp from the moisture in the concrete. 

Planed lumber is more easily cleaned and the concrete does not 
stick to it so easily. Use lumber planed on one face and two edges 
to insure a tight job. 

Tongued and grooved boards will be a little more expensive but 
insure an exceptionally nice job. 

Grease the forms with soap, linseed oil or crude oil to keep the 
lumber free of the concrete. Although some do not do this it is much 
the better way. , 

Be positive all forms are absolutely vertical, especially forms for 
walls or piers. Use a spirit level or a plumb bob. Do as little pound- 
ing as possible near fresh concrete. 

Length of Time Forms Should Be Left in Place 
This depends on the nature of the construction. 
For small construction work, where the concrete bears no weight, 
the forms may be removed as soon as the concrete will bear its own 
weight, that is, some time between 12 and 48 hours after the concrete 
has been placed. 

Where the concrete must resist earth or water pressure — as in re- 
taining walls or dams — the forms should be left in place until the con- 



22 



ELEMENTARY CONCRETE CONSTRUCTION 



crete has developed nearly its final strength (this may be 3 or 4 
weeks, if the weather is damp or cold, or anything else prevents quick 
curing). 

Various Surface Finishes for Concrete 
Mortar Finish 

Facing concrete with a coat of mortar plaster is often a trouble- 
some undertaking because it is difficult to obtain a strong enough 
bond — that is, a strong enough cohesion — between the concrete mass 
and the surfacing mortar. The mortar should be applied in as thin a 
layer as possible. The proportions are 1 part Portland cement and 2 
parts sand. Opinions vary as to the exact proportion of cement and 
sand in cement mortar, varying from 1 part cement and 1 part sand 
to 1 part cement and 2y 2 parts sand. The character of the job should 
be considered and a proportion of sufficient strength to fit the proposi- 
tion at hand decided upon. However, a mixture of 1 part cement to 
2 parts sand may be considered a good all around proportion. 

Before applying the surfacing mortar see that the whitish scum on 
the old work is removed, as it has no strength in itself. This may 
be done if the work has just had the forms removed, by using a wire 
brush vigorously. If the concrete is hard the surface scum cannot be re- 
moved unless the surface is roughened with a cold chisel. Whichever 
method of removal is used the aggregate of the concrete must be ex- 
posed, or the newly deposited concrete or mortar will not bond to 
the old. 

In placing a mortar facing on a concrete surface, drench the wall 
thoroughly with water not more than 30 minutes before the applica- 
tion of the mortar, and brush the surface with a thin cream made of 
cement and water. 

This cream should be mixed in small batches as the work pro- 
gresses and should be used within 30 minutes after it has been mixed, 
as it loses its strength after that length of time. 

Trowel the mortar facing on the surface after this preparation, and 
press the mortar firmly to a smooth uniform surface. 

Sprinkle the mortar surface with water twice a day for about 10 
days. This is a positively necessary precaution, because facing can- 
not develop its full strength unless it has moisture applied continu- 
ously throughout the time it is hardening. If drying is too rapid, 
there will be excessive shrinkage and the surface will check and show 
hair cracks. 

Whenever it is possible, apply the mortar surfacing or wearing 
surface as in sidewalks, floors, etc., at the same time as the base or 
main mass of concrete. This gives far more satisfactory results and 



BRUSH SURFACES 23 

makes a perfectly solid mass, like one huge stone, therefore causing' 
no difficulties in bonding. 

Brush Surfaces 

One of the best methods of removing the plaster from the forms 
is as follows : After removing the forms concrete should be brushed 
while green with a steel brush or one made of stiff fiber bristles. If 
the concrete hardens so that the mortar cannot be brushed away from 
the coarse aggregate, the mortar may be softened by a solution of 
muriatic acid. After brushing, the work should be treated with an 
acid solution and for this purpose the solution should be 1 part of com- 
mercial muriatic acid to 3 parts of water. After the use of an acid 
solution the work should be washed immediately, and thoroughly, 
with clean water, as any acid remaining on the surface of the work 
will ultimately cause streaks and discolorations. 

The following materials are recommended as suitable aggregates 
for the production of desirable brush surfaces, it being understood 
in using any of them for aggregates that the mixture is to be 1 sack 
of Portland cement to 2y 2 cu. ft. of aggregate. 

Yellow marble screenings up to ]/\ in. ; red granite screenings up 
to 34 i n - '■> black marble graded from y% to y 2 in. ; river or lake gravel 
graded from J4 to Y XXi - ^° secure economy, limestone may be sub- 
stituted for white marble and either black granite or trap-rock may be 
substituted for black marble. 

The above materials are merely suggestions of the possibilities of 
concrete surfaces. Infinite variations may be made by substitutions 
in combining materials, while if one takes trap-rock, red granite or 
limestone, for instance, by merely increasing or diminishing the size 
of one or two of the ingredients it readily will be seen that a great 
many combinations may be effected, all of which will produce desir- 
able surfaces for brushing. In general fine aggregate will produce a 
comparatively smooth surface of uniform color while coarser aggre- 
gates will give greater irregularity in both surfaces and color, pro- 
ducing a somewhat rustic appearance. 

One of the chief advantages of finishing surfaces by brushing is 
the adaptability of this process to every class of concrete construction. 
Park benches, lawn vases, lamp-posts and statuary of all kinds may be 
finished by this process as easily as buildings. 

Rubbed Surfaces 

Where it is desired to leave a smooth surface in the shape produced 
by the forms, but to obtain a more finished surface than possible by 
washing with a float under which sand is used for cutting, the con- 



24 ELEMENTARY CONCRETE CONSTRUCTION 

crete may be finished, when it is at an age of from 1 to 2 days, by 
removing the form and rubbing the surface with a brick and sand, 
natural stone, emery, or carborundum. 

Where it is desired to finish concrete in this manner the large 
pieces of aggregate should be spaded back from the forms so that the 
face will contain little or no coarse aggregate. If a mottled surface 
is desired it may be produced by a mortar composed of 1 part of Port- 
land cement and 2y 2 parts of white marble or limestone, either of 
which will rub to a very beautiful surface. While the rubbing is in 
process a thin grout, composed of 1 part of cement and 1 of sand 
should be applied and well rubbed in. The work should afterwards 
be washed down with clear water. 

Dressed Surfaces 

When concrete is thoroughly hardened, it may be dressed in the 
same manner as natural stone, although the stone cutter's tools require 
slight alterations to suit the need of concrete. While this work is 
sometimes done on concrete when it is 2 or 3 days old, the best results 
are obtained when it is about 1 month old. The great disadvantage 
of dressing concrete with a stone hammer at too early an age is that 
pieces of the aggregate will be knocked out from the cement mortar, 
leaving unsightly holes, while if left for a few weeks it will become 
so thoroughly hardened that they will break under the hammer and 
give a uniform surface much the same as natural stone. For this pur- 
pose the best tool is a special form of bush hammer, designed to dress 
concrete, the points on the face of which are farther apart and larger 
than the regular stone cutter's hammer. A three pound hammer with 
four points is a good size for concrete work, although larger ones are 
frequently used. Another hammer which has been especially designed 
for dressing concrete is similar to a pick having five teeth on each 
end. For finishing large surfaces a pneumatic hammer is used and 
produces a very uniform finish, doing the work much more rapidly 
than where the tools are operated by hand. Another finish is obtained 
by an expensive machine which gives a sand-blast finish. 

Concrete should never be subjected to sand-blasting until it is at 
least one month old. A nozzle pressure of from 50 to 80 lbs. should be 
maintained. 

Colored Surfaces 

For artistic work, the suggestions already made with reference to 
the selection, gradation and mixing of aggregate will accomplish better 
results in any process of artificial coloring which may be adopted. 



DESIGN 



25 



There are, however, possibilities of producing- artificially colored con- 
crete work of which some notice should be given. 

The coloring-matter should not exceed 5 per cent of the weight of 
the cement and should be mixed with the dry cement before water is 
added. Nothing but mineral coloring should be used. The following 
table taken from "Cement and Concrete," by L. C. Fabin is generally 
accepted as authority for mounts of a different color and material. 

COLORED MORTARS 
Colors Given to Portland Cement Mortars Containing 2 Parts River Sand to 1 of Cement 



Dry Material Used 



Lamp black 

Prussian blue. . . . 
Ultramarine blue. 



fellow ocher. 
Burnt umber. 



Venetian red 

Chattanooga iron ore. 
Red iron ore 



Weight of Coloring-matter Per Bag of Cement 



Light slate 
Light green slate 



Light green 
Light pinkish 

slate 
Slate, pink tinge 

Light pinkish 

slate 
Pinkish slate 



1 lb. 



Light gray 
Light blue slate 
Light blue slate 



Pinkish slate 

Bright pinkish 

slate 
Dull pink 



Dull pink 



2 lbs. 



Blue gray 
Blue slate 
Blue slate 



Dull lavender 

pink 
Light dull pink 

Light terra-cotta 

Terra-cotta 



4 lbs. 



Dark blue slate 
Bright blue slate 
Bright blue 

slate 
Light buff 
Chocolate 

Dull pink 

Light brick red 

Light brick red 



There will be exceptional cases where it is necessary, or desirable, 
to color concrete surfaces after the surface has been completed. For 
this purpose cement paint should be used, several brands of which 
are now manufactured, in a limited number of colors, by reputable 
companies. 

Design 

There remains only one further feature of concrete surfaces to be 
discussed and that is the producing of mosaics or pattern work. The 
plasticity of concrete makes it lend itself particularly to the reproduc- 
tion of beautiful designs which may be secured in a variety of ways. 
For the more elaborate designs the pieces of marble, if that be the 
material selected, should be glued face down upon tough paper, in the 
same manner in which floor tiles are prepared for laying. This paper, 
with the design upon it should be placed in the forms and the concrete 
rammed in place. After the forms are removed, and the concrete al- 
lowed to harden, the paper should be removed by wetting. Then clean 
the face of the finished design by the usual acid solution 3 parts of 
water to 1 part of commercial muriatic acid. 

Waterproofing Concrete 

Concrete made from carefully selected materials, properly mixed 
and properly placed, under ordinary conditions should be watertight. 

All the waterproofing materials in the world will not insure a tight 
job unless the foregoing conditions are met. 



26 ELEMENTARY CONCRETE CONSTRUCTION 

The Use of Concrete in Winter 

Indoor concrete work such as floors, the making of concrete posts, 
etc., is quite feasible during the winter providing the temperature 
where the work is being done does not go below 45°. Outside work, 
requires considerable care during cold weather and the aggregates 
must be properly heated before being used. . This is usually done on 
small work by having a hot fire under a metal arch on which the sand 
or gravel may be thrown. 

Warm water should be used in mixing and the finished job prop- 
erly protected with straw or other materials until it has obtained a 
sufficient set to prevent freezing-. 

Estimating 

The first step in calculating quantities is to figure the total cubic 
space to be occupied by the concrete. This is done by reducing all 
dimensions to like units, such as multiplying length, width or height, 
and thickness together in feet or fractions thereof. 

For illustration, if a walk was to be laid 75 ft. long, 6 ft. wide and 
6 in. thick, we would have 75 x 6 x y 2 or 225 cu. ft. Dividing this by 
27, which is the number of cubic feet to a yard, we have 8^ cu yds. as 
the volume to be filled with concrete. 

Figuring a foundation. We will assume that we have a house 
foundation 1 ft. thick, 10 ft. high, 28 ft. wide and 42 ft. long. 

This would figure 1 x 10 x 26 or 260 cu. ft. for the short wall and 
1 x 10 x 42 or 420 cu. ft. for the long wall. In the short wall 26 is used 
instead of 28 because we figure the long wall the full length or 42 ft. 
We must lessen the width, therefore, by 2 ft. (1 ft. on each end) to 
allow for the thickness of the wall itself, which is 1 ft. 

Since there are two short walls and two long walls, it is necessary 
to double the totals 260 and 420, making them 520 and 840, totaling 
1,360 cu. ft., from which must be deducted window and door spaces. 

Assuming that there are two doors 7 ft. x 3 ft. and eight windows 
3 ft. x 2 ft., there must be deducted the following amounts : Two doors 
would equal 7x3x1x2 or 42 cu. ft., eight windows, 3x2x1x8 or 
48 cu. ft., totaling 90 cu. ft. This leaves the total cubical contents 
1,360 less 90 or 1,270 cu. ft. 

It is always necessary, in measuring the height of walls, to take 
into consideration the depth that the footings or foundations go into 
the ground and if the footing is thicker below the ground than above, 
as is quite common, it is better to figure their volume separately. 

In figuring curved work, such as a road, which is crowned, the 
average thickness should be taken. 



QUANTITIES OF MATERIALS 



27 



Table for Determining the Quantities of Materials Needed 
The following table will enable you to figure the quantities of each 
material needed for any job, by adding together or multiplying the 
quantities in the table corresponding to the volumes in the first col- 
umns. The first column shows the quantity of concrete. The other 
five divisions show the different mixtures and quantities of material 
under each mixture needed to produce the quantity of concrete given 
in the first section. 





1 : 1% : 3 Mixture 1:2:3 Mixture 


1:2: 


4 Mixture 


1 :2% 


: 5 Mixture 


1:3:6 Mixture 


"S3 

. a> 
+> u 
«t-i u 

. c 

3 C 


« a 


0'S 






rf9 


ii * 




3 S3 




c 

to S 


£t3 


3.S 


e 
m o> 

ta £ 
ca V 


• C 
3 8J 


*2 


oc 


eao 


Otfl 


OCQ i PQO 


OW 


OW 


MO 


OK! 


ora coo 


OW 


ora 


coo 


Otfl 


OW 


100 


28 


42 


84 


25% 


51% 


77% 


22 


44 


88 


18 


45 


90 


16 


48 


96 


90 


25% 


37% 


75% 


23V 5 


46% 


69% 


19% 


39% 


79% 


16% 


40% 


81 


14% 


43% 


86% 


80 


22% 


33% 


67y 5 


20% 


41% 


62 


17% 


35% 


70% 


14% 


36 


72 


12% 


38% 


76% 


70 


19% 


29% 


58% 


13 


36 


54 


15% 


30% 


61% 


12% 


31 y 2 


63 


11% 


33% 


67% 


60 


16% 


25 y a 


50% 


15 % 


31 


46% 


13% 


26% 


52% 


10% 


27 


54 


9% 


28% 


57 % 


50 


14 


21 


42 


13 


26 


39 


11 


22 


44 


9 


22% 


45 


8 


24 


48 


40 


n% 


16% 


33% 


10% 


20% 


31 


8% 


17% 


35% 


7% 


18 


36 


6% 


19% 


38% 


30 


8% 


12% 


25y 5 


7% 


15% 


231/4 


6% 


13% 


26% 


5% 


13% 


27 


4% 


14% 


28% 


20 


5% 


8% 


16% 


5% 


10% 


15% 


4% 


8% 


17% 


3% 


9 


18 


3% 


9% 


19% 


10 


2% 


4y 5 


8% 2% 


5% 


7% 


2% 


4% 


8% 


1% 


4% 


9 


1% 


4% 


9% 


9 


2% 


It 


7% 


2% 


4% 


7 


2 


4 


8 


1% 


4 


8 


1% 


4% 


8% 


8 


2% 


6% 


2 


4% 


ey 4 


1% 


3% 


7 


1% 


3% 


7% 


1% 


3% 


7% 


7 


2 


3 


6 


1% 


3% 


6% 


1% 


3 


6 


iy 4 


3% 


6% 


1% 


3% 


6% 


6 


1% 


2% 


5 


1% 


3% 


4% 


1% 


2% 


5% 


1 1/10 


2% 


5% 


1 


3 


6 


5 


1% 


2 1/10 


4% 


1% 


2% 


4 


1 1/10 


2% 


4% 


9/10 


2% 


4% 


% 


2% 


4% 


4 


1% 


1% 


3% 


1 


2 


3% 


% 


1% 


3% 


7/10 


1% 


3% 


% 


2 


4 


3 


% 


1% 


2% 


% 


1% 


2% 


% 


1% 


2% 


% 


1% 


2% 


% 


1% 


3 


2 


ft 


Vs 


'8 


% 


1 


1% 


ft 


% 


1% 


% 


9/10 


1% 


ft 


1 


2 


1 9 32 


ft 


y 4 


% 


% 


7/32 


ft 


% 


% 


1/20 


1 


5/32 


% 


1 



To figure out how many cubic feet there are in a job, write down 
the dimensions, all in feet or fractions of feet, so that the result will 
be in cubic feet. To find the number of cubic feet in a pavement 30 
ft. long, 4 ft. wide and 4 in. thick, write the last dimension in feet, call- 
ing it 4 12 or 1/3 ft. Then multiply 30x4x1/3 and the answer will be 
40 cu. ft. Look in the table under the mixture you are going to use — 
opposite 40. Take the quantities there for your job. 

Example : If you want to know the materials for 291 cu. ft. of 
1-2-4 mixture, copy out the figures for 100 cu. ft. and multiply them 
by 2, to make 200. You will have 44 bags of cement, 88 cu. ft. of sand 
and 176 cu. ft. of stone. Then look under the same head, opposite 90 
cu. ft.: 19 4/5 bags of cement, 39 3/5 cu. ft. of sand and 79 1/5 cu. ft. 
of stone. Then look opposite 1 cu. ft. and you find 7/32 bags of ce- 
ment, 7/16 cu. ft. of sand and % cu. ft. of stone. Adding these three 
results you will find 291 cu. ft. of concrete in a 1-2-4 mixture will re- 
quire 64 bags of cement, 128 cu. ft. of sand and 256 cu. ft. of stone or 
gravel. 

For a wall, slab or a roof, you will find it easy to calculate the total 
cubic feet of concrete if you will just remember that you must mul- 
tiply together the three different dimensions, all expressed in feet or 
fractions of feet. 



28 ELEMENTARY CONCRETE CONSTRUCTION 

For more complicated jobs do not count corners twice, as there is 
a liability of doing, on walls, for instance. 

If you are building a trough, 12 ft. long, 6 ft. wide with walls 6 in. 
thick and 48 in. high, the two long walls will be 12 ft. long, 4 Jit. high 
and 6 in. thick, but the two other walls will be only 5 ft. long, 4 ft. high 
and 6 in. thick, — because the 6 in. thickness comes off the end of each 
of the short walls at each end. 

If a square tank or a room or anything hollow is being built, in 
which the proportioning of materials is the same in all its parts, figure 
on the whole thing as if it were solid and then subtract the cubical 
contents of the hollow part in the center. 

For instance, find the number of cubic feet of concrete for a tank 
10 ft. long, 10 ft. wide and 8 ft. high with walls, floor and roof all 6 in. 
thick, by first calculating the contents of the whole thing as if it were 
solid. This would be 10x10x8 or 800 cu. ft. Then figure the contents 
of the hollow inside. Allowing for the 6 in. walls, the inside measure- 
ments would be 9 ft. long, 9 ft. wide and 7 ft. high, or 9x9x7 equalling 
567 cu. ft. Subtracting this from the former figure (800 — 567), the 
answer will be 233 cu. ft. 

To calculate circular work there is one rule to remember : The area 
of a circle is found by multiplying the diameter by the diameter, then 
multiplying the result by 3 1/7 and dividing by 4, so that a circular 
slab of concrete 7 ft. in diameter would have an area of 7x7x3 1/7 
divided by 4, which equals 38^2 sq. ft. 

Multiply the area by the thickness in feet or fractions of.feet there- 
of, and you have the number of cubic feet in the slab. If this slab is 6 
in. thick, the number of cubic feet in it will be 3Sy 2 xy 2 or 19^. 

If you are building a circular tank, figure the total contents as if 
it were solid right through ; then calculate the contents of the hollow 
space that is not to be filled with concrete and subtract this from the 
first total. 

Mortar 

1 bag cement 2 cu. ft. sand make 2 1/10 cu. ft. mortar. 

1 bag cement 2% cu. ft. sand make 2% cu. ft. mortar. 

1 bag cement 3 cu. ft. sand make 2% cu. ft. martar. 

Concrete 

1 bag cement 1% cu. ft. sand 3 cu. ft. gravel or stone make 3^2 cu. ft. concrete. 

1 bag cement 2 cu. ft. sand 3 cu. ft. gravel or stone make 3 9/10 cu. ft. concrete. 

1 bag cement 2 cu. ft. sand .4 cu. ft. gravel or stone make 4% cu. ft. concrete. 

1 bag cement 2% cu. ft. sand 5 cu. ft. gravel or stone make 5 % cu. ft. concrete. 

1 bag cement 3 cu. ft. sand 5 cu. ft. gravel or stone make 5% cu. ft. concrete. 

The mortar and concrete tables given above give the cubic foot 
quantities of mortar and concrete respectively resulting from each of 
the mixtures shown. See Plate 3. 



QUESTIONS AND ANSWERS 29 

The author will assume, in the problems following, that the student 
has familiarized himself with the previous text, especially that relating 
to the proportioning, mixing and placing of concrete in the forms. 

Questions and Answers 

1. Why should bank-run gravel be screened and the fine and coarse materials 
be reproportioncd before using in a concrete mixture? 

Most bank-run gravel contains a great deal more sand than is desirable in 
a concrete mixture. Sometimes this sand is twice as great in quantity as what 
would be best. If 75 per cent of bank-run gravel were fine material, the proper 
proportion of cement would vary widely from that required in case only 30 
per cent of a bank-run gravel were fine material. Only by separating the fine 
material (sand) from the coarse material (pebbles) can definitely specified 
mixtures be secured. 

2. How does a 1:6 mixture differ from a 1:2:4? 

Part of the answer to this question is suggested in the preceding answer. 
A 1:6 mixture is 1 cu. ft. of Portland cement to 6 cu. ft. of fine and coarse 
aggregates, mixed. The resulting volume would be approximately 6 cu. ft., 
while a 1:2:4 mix would produce a volume of about 4 cu. ft. In one case 
there are 6 cu. ft. of concrete containing 1 sack of cement as against a little 
over 4 cu. ft. containing the amount of cement. Evidently the latter mixture 
will have greater strength. 

3. How wet should concrete be mixed for average work to secure' 
the greatest strength? 

For most construction, concrete should be of a quaky consistency, which 
means that when placed in a pile it will gradually spread out or flatten of 
its own weight. If more water than is required to produce a quaky con- 
sistency is used, the cement-sand mortar and pebbles will most likely separate, 
resulting in porous pockets in the construction. 

4. When should sand and gravel be washed before using in a concrete 
mixture and whyt 

If the sand or pebbles are coated with clay for instance, the cement can- 
not adhere to the surface of these particles. Therefore the cement cannot 
perform its binding function. 

5. How may sand and gravel be easily and quickly washed? 

A washing and screening apparatus may be readily constructed for a 
small outlay, by making a trough having a Y% in. mesh screen at one end, 
then raising and propping up the other end in which the materials are placed, 
attaching a pipe or hose at this end so that water may be supplied to tumble 
the material about, down the trough and over the screen at the lower end. 

6. What is the largest size aggregate permissible in a concrete mixture? 
There is a general rule in concrete construction, which specifies that no 

aggregate (pebbles or broken stone) shall exceed in size one-half the wall 
thickness in which it is used. As a rule, however, \y 2 in. is fixed as the maxi- 
mum for most work, while in thin walls, where reinforcing must be surrounded 
perfectly, it is often advisable to use a smaller maximum. Again, in the case 
of fence posts, there is a limit of size usually fixed at 3/i in - owing to the 
fact that the space to be filled with concrete is small. For much foundation 
work it is often permissible to exceed \y 2 in. maximum but generally speaking 
the maximum should not be more than 2 in. 

7. What method should be used to finish a concrete floor to prevent the 
surface from being slippery? 

Floors such as feeding floors and barnyard pavements should be finished 
with a wood float instead of a steel trowel. The former will produce an even 
but sufficiently gritty surface to make a non-slippery floor. 

8. How long a time should elapse after a floor has been constructed before 
it should be put into use? 

The time which concrete floors must be allowed to harden before putting 
them into use depends largely upon prevailing weather conditions and whether 
proper protection has been given the floor to enable the concrete to acquire 
strength under favorable conditions. Generally speaking, the time may vary 
from 10 days to 3 weeks. 

3 



30 ELEMENTARY CONCRETE CONSTRUCTION 

9. What protection should be given to concrete after it is placed to insure 
Proper hardening? 

All concrete construction which exposes a large surface to the air should 
be kept moist by some such protective covering as sand, burlap or canvas, 
to prevent rapid drying from the action of sun and wind. This covering should 
be kept moist by frequent sprinkling as often as necessary until the concrete 
has acquired the desired hardness. 

10. What slope should a floor have to provide the necessary drainage? 
One-eighth in. to the foot is sufficient. 

11. What thickness should a concrete feeding floor have? 

If the construction is one-course of a 1:2:3 mixture the floor should be 
not less than 5 in. thick. If of two-course construction then there should be 
a l:2y 2 :S base with \y 2 in. or 2 in. of 1:3 mortar surface, making the floor 
not less than 6 or 7 in. thick. 

12. Is a cinder fill under such a floor necessary? 

Not unless the conditions where the floor is to be laid are such that the 
underlying soil will collect and retain moisture. Even then, the cinder or 
gravel fill should be connected with a drain that will prevent water from 
being retained beneath the floor. In any case it is best to have the floor 
above the level of the surrounding soil. 

13. Hoiv will concrete construction save the liquid content of manure? 

The concrete feeding floor or barnyard pavement should slope toward 
a gutter that leads to a concrete manure pit. In this way all of the liquid 
content of manure is preserved. Likewise, the surroundings are made more 
nearly sanitary. 

14. Why is concrete usually the most economical material to use for farm 
improvements? 

Concrete is fireproof, rot-proof, rat-proof, sanitary, and reduces the labor 
of caring for stock. 

15. Can concrete zuork be successfully carried on in cold zveather? 

If sand and pebbles and mixing water are heated and the concrete is 
properly protected against freezing for at least 48 hours after being placed, 
much successful work can be done in cold weather. 

16. What feature of design should a concrete ivater tank or trough have to 
prevent cracking due to the freezing of the water? 

There should be a slope or batter on the inside so that when ice forms the 
expansion will cause it to slide up the tank sides, thus relieving the tank of 
pressure outward from ice within. 

17. Is barbed voire a suitable reinforcing material for concrete? 

Barbed wire should not be used as reinforcing material for concrete 
construction. It is difficult to handle and keep in position while concrete is 
being placed. Furthermore, it lacks the qualities which reinforcing steel 
should have for best results in concrete work. 

18. In what ivay may rust be objectionable on reinforcing steel? Is there 
danger of the steel rusting after encased in concrete? 

Unless the rust on the steel is in the form of a loose scale, it will do 
no harm. Once the steel is thoroughly embedded in concrete of proper 
consistency and density, it is protected against further rust. 

19. Is zvaterproofing necessary to produce watertight concrete? 

No waterproofing is necessary if the concrete mixture is properly pro- 
portioned for maximum density and carefully placed at a right consistency, 
and protected from rapid drying while hardening. 

20. Hoiv can concrete be prevented from sticking to the molds or forms? 
For some work a thorough wetting down of forms is often all that is 

required to prevent concrete from sticking. Sometimes soft soap, or a mix- 
ture of equal parts of boiled linseed oil and kerosene is used. Wetting down, 
however, is necessary at each use of the forms. 



PART II 

Problems 



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A CONCRETE BRICK 33 

A Concrete Brick 

(Practice Problem) 

Plate 5 shows the drawing of a form for making a concrete brick, 
2y 2 in. thick by 4% in. wide by 10 in. long. 

This problem is designed chiefly to familiarize the pupil with the 
making of a simple form and the proportioning, mixing and casting of 
concrete. 

The base-board for the form is 5^ in. x 12 in., made from ]/$ in. 
material. The ends are % in. x 4 J /s in. Two of these are required. 

The two sides are Y% in. x 2y 2 in. x 12 in., with two blocks Y% in. x 
]4 in. x 2y 2 in. attached y$ in. in from the ends with screws, as shown. 

Mix the necessary amount of cement and sand in proportions of 
1 part cement to 3 parts sand as described in chapter under "Mixing. " 

Place a wooden clamp in place shown in sketch and leave 24 hours. 




Illus. 7. Concrete Steps Laid by Eighth Grade Boys. 



34 




ANCHOR WEIGHT 35 

Anchor Weight 

Plate 6 shows the drawing of the form for a concrete anchor weigh- 
ing about 25 lbs. 

This problem, while a very little more difficult than that of Plate 
5, is simple enough in construction for a fifth or sixth grade boy. 

The two larger sides A, are cut 9 in. x 10^ in. and then tapered 
on one end to 8 J / 2 in., as shown. 

Attached to the two sloping edges are two pieces % in. x % in. x 
9% in. 

Sides B are first cut 7 in. x 9 in. and tapered to 5 in. 

The base C is % in. x 8^4 in. x 10^2 in. The top and bottom edges 
of A and B are leveled as indicated in sketch. 

Two scrap sticks are partly nailed on to the edges of sides A, as 
shown, and the ringbolt suspended while the form is being poured. 
The sides A are also lightly nailed to the base so as to be easily re- 
moved when the form is hard. Leave in the form 24 hours. 

An interesting feature of this problem is the figuring out before- 
hand of the weight of the anchor. This is done as follows : 

The shape of the anchor is in the form of a truncated pyramid. It 
is necessary to first find the cubical contents, which is obtained by 
taking a section through the average height, which is 4 J / 2 in. perpendic- 
ularly up from the base (the total height being 9 in.). This gives us 
the average section, square in shape, and 6 in. on a side. 

The area of this section is then 6 in. x 6 in. or 36 sq. in. Multiply- 
ing this by the height, 9 in., we have 36x9 in., equalling 324 cu. in. in 
volume. There being 1728 cu. in. in a cubic foot, we have 324 cu. in. 
divided by 1728, which equals 3/16 cu. ft. 

A cubic foot of concrete weighs from 130 to 140 lbs. varying ac- 
cording to the kind of crushed stone used, granite being the heaviest. 

Taking 135 lbs. as the average weight we find that 135 divided by 
3/16 equals 25 5/16 lbs., the weight of the anchor. 

The writer has found that the boys are extremely interested, after 
figuring out beforehand the weight of the anchor, to verify their cal- 
culations by actually weighing the finished problem. 

A very serviceable horseweight can be cast, on the same principle, 
by reducing the dimensions of the form. 



MISCELLANEOUS PROBLEMS 



37 



Miscellaneous Problems 
Plate 7 gives a few simple miscellaneous problems in concrete and 
arc self-explanatory. 




Illus. 8. Concrete Steps and Walk Laid by Eighth Grade Boys 



38 




CONCRETE ROLLER 



39 



Concrete Roller 

Plate 8 shows drawings and sketch of a concrete roller weighing 
about 265 lbs. and is suitable for rolling lawns, etc., requiring two men 
to operate. 

The form for this roller is made from a piece of sheet iron cut 24 
in. by 56^ in. The edges must be cut square and even. Make two 
sets of wooden clamps, like the circular form shown in the drawing. 
Bend the piece of sheet iron in a circle and nail, if necessary, to the 
two wooden clamps. Wire the iron form or jacket with No. 16 wire 
to hold the form from opening at the joint when the concrete is placed. 
Grease or oil the inside of the form thoroughly so that it will not stick 
to the concrete. To make an opening through the center of the roller 
for the axle or shaft, place a Y\ in. or ]/% m - iron pipe in the center of 
the form. The axle can be cast in the roller itself if desired instead of 
casting a Y\ in. or J/% in. pipe in the roller in which to place the axle. 

The concrete should be made of 1 part cement, 2 parts of sand and 
4 parts of stones or gravel. It will take a little less than 1 bag of ce- 
ment for a roller of the above dimensions. 

The handle may be made of 1 in. iron bent and welded together as 
shown in. the figure. A discarded lawnmower handle could be used 
and the iron work bolted to the same. 

A smaller roller for rolling seeded ground or golf greens may be 
made by pouring concrete into a piece of pipe which forms the outside 
surface. 




Illus. 9. Tearing Up Old Tar and Gravel Walk, Old Walk to Be Used 
as Large Aggregate in New Concrete Walk. 



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HORSE-BLOCK 41 

Horse Block 

Plate 9 shows the method of making a form for a horse block. 

Horse blocks can be built solid in place or they may be cast in a 
form like the drawing with paneled sides. 

Make the forms as shown in the drawing so that the inside dimen- 
sion is 10 in. high, 22 in. wide and 28 in. long. 

The panels for the sides are % in. x 6 in. x 24 in. and those for the 
ends % in. x 6 in. x 18 in., leveled as shown. These should be placed 
carefully in the center of the sides and ends and attached firmly in 
place with nails or screws. Make the four braces % in. x % in. x 10 in. 
and screw them in place. Nail the two cross braces lightly across the 
top so they may be easily removed. 

Grease the forms thoroughly and fill with a mixture of 1 part ce- 
ment, 2y 2 parts of sand and 5 parts of gravel or broken stone. 

Smooth off the top surface with a trowel when first laid, then in a 
few hours scrape off any light colored scum with a wire brush or horse 
curry comb, and trowel the surface again, preferably with a wood float, 
but using no fresh mortar. 

The form should be removed in 24 hours, or as soon as it is hard 
enough not to show thumb marks, and while the concrete is still green 
rub down the sides w r ith a wood float or brick. Keep damp by sprin- 
kling for a week. 




Illus. 10. Showing Gravel Sub-Base, Rough Concrete Undercoat and the Top or 

Finished Coat. 



42 







CONCRETE DISH FOR BULBS 43 

Concrete Dish for Bulbs 

Plate 10 shows a simple design for a concrete dish suitable for 
bulbs. 

The sectional diagram will explain the method of making the form 
and there is a good chance here for original designing. 

The form is made in two parts, the outer box form and the inner 
core. 

Assemble the box and core, suspending the core as shown in Plate 
11, by means of a small cross brace of scrap wood. 

The forms should be thoroughly greased and the concrete mixed 
1 part of cement to 2 parts of sand. 

Reinforcing' should be used consisting of y 2 in. galvanized square- 
mesh wire, which is placed in position by making a basket so that 
when put in place in the form, it will be half way between the upper 
and lower surface of the concrete. 

This basket may be held in place by slipping blocks between it and 
the inside form, these to be removed after the concrete has been de- 
posited a little over half way up the forms. A trowel or a thin flat 
stick with a chisel end, should be worked up and down along the in- 
side of the form so as to force the coarse particles of the mixture away 
from the surface. 

First place a layer of concrete in the bottom of the form, then set 
the wire reinforcing basket on this. Add more of the mixture, work- 
ing it into all corners, then press the core into place and fill up the 
sides thoroughly using the chisel end paddle to help fill in. 

Leave in the mold at least 24 hours and then use a great deal of 
care when removing so as not to damage the green concrete. 

After the form has been removed the outside surface of the con- 
crete should be brushed with a stiff brush. The dish should then be 
allowed to air-dry for 2 or 3 hours, but be kept from drying out too 
rapidly ; never place in the sunlight. 

The dish should then be carefully placed in water and allowed to 
soak for two or three days. 

A very smooth surface may be obtained by sprinkling dry cement 
over the wet surface, after removing from the water, and rubbing the 
cement in with a scrubbing brush or with a block of cork. 

Flower Boxes 

Plates 11 and 12 are drawings showing construction of flower boxes 
of concrete. These are made up, cast and finished the same as the 
bulb dish in Plate 10. 



44 




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CONCRETE HITCHING POST 47 

Concrete Hitching Post 

Plate 13 gives the method of making a form for a concrete hitching 
post. 

The finished post is 5 ft. tall, tapering from 6 in. square at the base 
to 4^4 in. square at the top. 

The forms are made to the dimensions shown on the drawing with 
cleats screwed to the wider sides as shown. 

If the ringbolt is to be placed at the top a cap 6^4 in. x 8% in. is 
attached at the upper end and a ringbolt of any desired size suspended 
from it. 

This cap is made in two pieces, 3^ in. x 8^4 in., with a hole through 
which the ringbolt is placed. 

This problem brings in reinforcing with Y\ in. iron rods placed as 
indicated in the section. 

The form may be made according to method No. 1, where the post 
lays on its side and the concrete is placed from the upper side and 
smoothed, or it may be made as in method No. 2 where the form is 
tube-like and the concrete poured in at the lower end. 

The post should not be handled or moved inside of a week, as it is 
liable to crack. 

Let the post dry out for about two weeks before using and keep 
it damp by sprinkling with water daily. 

Posts similar in design but on a larger scale could be made up to 
be used as clothes posts. 






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CONCRETE FENCE POSTS 49 

Concrete Fence Posts 

Concrete fence posts are coming more and more into general use, 
due not only to their permanency but also their greater strength. 

Plate 14 shows the method of casting individual posts and also a 
combination form for casting four posts at a time. 

In the drawing of the section of the single form there is shown the 
methods of reinforcing- with hay bailing wire and % in. iron rods. 

These single posts are cast in a similar way to the hitching post 
shown in Plate 13. 

The combination form may be easily taken apart, to remove the 
finished posts, and is a saving in time and material. 

A platform of matched boards is laid, 4 ft. wide by 8 ft. long, and 
on this the form proper is laid. The two outside pieces and the two 
ends are made from 2 in. x 4 in. material, while the inside separating 
boards are made up of 1 in. x 4 in. stock. 

Blocks are nailed at the corners, as shown, and wedges driven be- 
tween the blocks and the sides of the forms to hold in place. 

It will be noticed that the partitions and the end piece are 
notched in. 

The form should be properly greased before placing the concrete. 

To fill this form once, that is to make four posts of the size given 
(using a mixture of 1 part cement, 2 parts sand and 3 parts gravel or 
crushed stone not larger than % in.) will require about 1 bag of 
cement, 2 cu. ft. of sand and 3% cu. ft. of stone or gravel. 

Iron rods for reinforcing must be used. First place 1 in. of con- 
crete and then place 2 rods on top of the concrete. 

Then fill to within 1 in. of the top of the forms, place the other 
2 rods, and finish filling. » 

Concrete fence posts must be carefully protected until they are 
hard. Don't move them until at least 10 days old or they will crack. 
Keep them moist by sprinkling and then store them out of the sun 
until they are at least a month old. 

There are several methods of fastening woven wire to concrete 
posts and four good methods are illustrated in the drawing. 

The screw eyes are inserted in the fresh concrete. The holes are 
made by placing 1 in. greased dowels in the forms and removing them 
when the concrete is about a day old. The wood strip is placed in 
the bottom of the form before placing the concrete and its tapering 
leveled edges hold it in the hardened concrete allowing the wire to be 
nailed direct to it. 



50 




CONCRETE SUPPORTS 51 

Concrete Supports for Parallel Bars 

Plate 15 gives a drawing of parallel bars suitable for the school 
playground. 

Plate 13 gives the method for making the form and casting posts 
of this description. The bars themselves consist of 2 in. galvanized 
iron piping, 8 ft., 6 in. long, with caps screwed on the ends. These 
bars are suspended in a pipe T which itself is attached to an upright 
piece of piping cast in the concrete, as shown. 

Reinforcing rods, ]/ 2 in. in diameter are placed, as in Plate 13, to 
add strength to the posts. 

These posts should remain in the forms at least 10 days, being 
constantly sprinkled. After removing from the forms they should be 
allowed to season for about a month before being used. When the 
posts are placed in the ground the hole should be made 3 or 4 in. larger 
all around than the posts and this space filled in with concrete and 
thoroughly tamped down. 



52 



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CONCRETE SAND BOX 53 

Concrete Sand Box 

Another interesting addition to the playground equipment is the 
concrete sand box shown on Plate 16. 

This may be made of any desired size, the one shown in the draw- 
ing being 8 ft. x 12 ft. and 20 in. high. The walls are 5 in. thick and 
extend 8 in. below the level of the ground. 

The method of placing the form is clearly shown. A trench is 
first dug as long and deep as needed and after the form is set in place 
the concrete, consisting of a mixture of 1 part cement, 2 parts sand 
and 4 parts gravel or broken stone, is poured. 

The forms should be removed in about 48 hours and the surface 
of the concrete rubbed down with a wet brick, using a neat cement 
mixture under the brick to help smooth up the surface. The concrete 
should be protected for about a week, wetting down each day. The 
concrete box should then be filled three-quarters full of clean, sifted 
sand. 



54 






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LAWN PEDESTALS 55 

Lawn Pedestals 

Plate 17 shows the drawing of two simple lawn pedestals, the first 
having a circular shaft and the second a shaft square in section. 

The shaft for the first pedestal is cast in a similar manner to the 
concrete roller, using a piece of galvanized iron bent to a 6 in. diameter 
and 24 in. long. The supports are made of wood with a hole cut in 
them of sufficient size to allow the shaft form to pass through. 

The top form should be turned down on a lathe out of a plank 
2>y 2 in. thick, or of built up stuff, as shown in the sectional view. 

The sub-base is cut from \y 2 in. stock with a hole 9 in. in diameter. 
The base is hexagonal in shape and is held together by patent corru- 
gated fasteners. 

A 24 m - ^ ron r °d about 8 in. long should be inserted in the center 
of the base, when being cast, and projecting enough to go through 
the sub-base and flush with the bottom side of the base proper. 

The top of the pedestal should be held in place in a similar way 
with the exception that the rod should not penetrate the top more than 
2 in. When assembling, each piece should have a thin layer of neat 
cement grout, consisting of cement and water, spread upon it to form 
an attaching mortar, to help hold the various parts together. 

The shaft should be reinforced with y 2 in. iron rods, 4 in number, 
placed at equal intervals, 1 in. from the surface. The top, sub-base 
and base should be reinforced with % m - wire mesh laid flatwise 
across their centers. 

After remaining in the forms for about 10 days they should be 
carefully removed and set away 3 or 4 weeks to season. Wet reg- 
ularly. 

Style B pedestal is very easily cast, the operation being similar to 
that of casting the hitching post, Plate 13, and reinforcing and assem- 
bling same as Style A. 

The pedestals shown on Plate 18 are made up similarly to Style B 
on the preceding plate, the only addition being in the paneling, which 
is provided for on Plate 9, in the drawing of the horse block. The 
method of making the form and constructing and placing the panels 
are self-evident in Plate 18. 

Sun-Dials 

The pedestals shown on Plates 17 and 18 can easily be made into 
excellent sun-dials by purchasing commercial dials and attaching 
them in the following manner. 

The sun marks on the trees and flowers the passing of the sea- 
sons, so it is fitting that on the dial-face it should mark the flight of 
the quiet hours spent in the garden. 



56 




SETTING OF THE SUN-DIAL 57 

Setting of the Sun-Dial 

The pedestal should be firmly placed on a foundation that reaches 
below the frost line. 

The plate is set with the base of gnomen pointing south, but as 
the true south varies from the magnetic meridian, a compass will not 
accurately determine the position. A more accurate judgment can 
be obtained by using a table of time variation which shows the daily 
discrepancies between sun and standard time. With the aid of this 
table the dial can be set by the sun, mid-day being the best time to 
make the adjustment. 

The dial plate must be level, and when 'properly adjusted, should 
be securely attached to the top of the pedestal with cement mortar. 

Concrete Garden Bench 

Plate 19 shows a drawing of a concrete garden bench, 

Plate 20 shows the details of the form construction. The top of 
the bench is cast on a base of sufficient size to hold the frame, which 
is 18 in. by 54 in. inside and 3 in. high. 

This is held by two cross braces temporarily nailed as shown. 

The top is reinforced, as indicated in Plate 19, by ^4 m - i ron rods, 
laid Y\ m - from the under surface of the seat. 

The end supports for the seat may be cast by either Method No. 1 
or Method No. 2, Plate 20. A little study of these drawings will show 
the method of construction. 

The ends should be dowelled into the top by means of Y\ in. iron 
rods, as shown on both Plates 19 and 20. 

The concrete mixture should be composed of 1 part cement, 2 
parts sand and 2 parts of crushed stone or gravel, averaging in size 
from % to ]/ 2 in. 

If however, no coarse aggregate is used, a 1 to 3 part mixture of 
cement and coarse sand should be used. 

After placing about Y\ in. of concrete in the mold, lay the reinforc- 
ing carefully as shown, continue filling the form, taking care to work 
the mixture into all corners carefully. This top surface will be the 
top of the finished seat, therefore it will pay to use care in finishing 
it to as smooth a surface as possible. An edger is run around the 
inside of the form to give a rounded edge to the top of the slab. 

The sides of the form may be removed in about 48 hours but the 
form under the slab should not be removed for at least 7 days. 

Original designs may be worked out in garden seat construction. 

Concrete Troughs 
Plate 21 shows the construction of concrete troughs suitable for 
feeding hogs. 



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CONCRETE WATERING TROUGH 61 

There are various methods of casting troughs and also various 
types of troughs. 

The drawing shown is a trough with a V shaped interior and the 
form is made similar to that of fence posts with the exception of the 
additional V shaped core in the middle. 

The drawing is self-explanatory and the reinforcing is placed as 
shown in the sectional sketch. Another method of casting the same 
style trough is shown together with a round bottomed trough with a 
smoothed up tree trunk core. 

On Plate 22 is shown still another method of obtaining a rounded 
interior, in this case the core being made up of clay shaped by means 
of a template, as shown. 

Style C, Plate 22, shows a flat bottom type trough with its box 
core. All reinforcing should consist of 34 m - i ron rods and fine mesh 
poultry wire. 

The forms should be thoroughly greased. The mixture for the 
concrete should be 1 part cement, 2 parts sand and 4 parts gravel. 
Tamp it lightly into place and smooth off the exposed surface. Let it 
stand until it is dry. Remove the inner forms and paint the inside 
with a cement grout mixed as thick as cream. Do not use the trough 
for at least 10 days. 

Wet down each day to insure drying out evenly 

Small Concrete Watering Trough 

Plate 23 gives the drawing for a small watering trough. 

The trough proper is cast in the same way that the hog trough on 
Plate 22, Style C, is done. This is cast separate from the ends. The 
reinforcing is the same as for the hog trough with the proportions of 
1 part cement, 2 parts sand and 4 parts gravel. 

The sketch shows very clearly the method of building up the end 
forms. These should be reinforced with y^ in. rods and poultry wire. 

If these forms are thoroughly greased the draft of the form will 
allow its being raised clear of the mould by the handles. The. forms 
may be removed in 24 hours and the concrete rubbed down with a 
brick dipped in cement grout or with a carborundum stone. 

Foundations for the two ends to set upon should be cast in the 
ground the proper distance apart and of the size shown on the 
drawing. 

Protect the newly cast trough for at least 2 weeks before using, 
wetting down daily. Arrange for intake and overflow pipes to meet 
local conditions. 

Circular Watering Trough 

Plate 24 shows a design for a circular watering trough which is 
very simple in construction. 



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WASTE WATER RECEPTACLE 65 

If it were not for the more complicated form work, the circular 
shapes would be built more frequently, because of the attractive effects 
which can be produced. 

Lay an old wagon or buggy tire on the ground and mark a line on 
the inside of the tire. Excavate the inside of the tire to the depth of 
6 in. and place endwise three 1 in. x 2 in. stakes about 3 ft. long on the 
inside of the tire. Raise the tire 2 ft. from the ground to make the 
total inside depth of the trough 3 ft., and drive a nailin each of the 
three stakes under the tire to support it at this height. Fill in the 
circle between these three stakes with slats or flooring boards set on 
end and place a nail in each, under the tire, to hold them at the top. 
To hold them at the bottom tamp a little sand at the foot of the stakes. 
Mix 1 part cement, \ l / 2 parts sand and 3 parts screened gravel or 
broken stone and lay about 4 in. of concrete. Place the reinforcement 
as described for rectangular troughs, running it up on the sides so that 
it is about 2 in. from the outside surface. After placing the reinforce- 
ment, the rest of the operations are the same as for the rectangular 
troughs. The inside form may be made by sawing a barrel in two, 
nailing each of the barrel staves to the head of the barrel and remov- 
ing all but the upper hoops. 

The remaining construction is clearly shown in the drawing. 

Allow for intake and overflow to suit local conditions. 

This type of trough will take about Zy 2 bags of cement and a single 
load of sand and gravel. A single load of sand or gravel is considered 
as 20 cu. ft., or % cu. yd., and a double load is 40 cu. ft. or nearly lj/ 2 
cu. yds. 

Treat the finished concrete as in the rectangular trough. 

Waste Water Receptacle 

The waste water receptacle shown on this same plate is constructed 
in a very similar manner to the circular trough, the great difference 
being that it is sunk in the ground further and has a cover and drain. 

The cistern itself can be made by using a cut off barrel, but no 
outer form is required as the earth wall, if fairly solid, will retain the 
desired shape if care is used in the excavating. 

The bottom of the cistern slopes toward a drain covered with a 
strainer. The water drains through a 4 in. outlet pipe, as shown. 

The cover is cast in a tire of suitable size and reinforced laterally 
with % m - i ron rods crossing each other at right angles and covered 
with poultry netting. A slight depression is made in the middle where 
a ringbolt is inserted to lift the cover by. 

Place the inlet pipe where it is convenient. 

Treat the finished concrete as for the rectangular trough. 



66 







STEPS AND PORCH CONSTRUCTION 67 

Concrete Steps and Porch Construction. 

Plate 25 gives a sketch of a typical set of steps and a small porch, 
together with details showing the method of constructing individual 
treads. 

Steps and stairs are of two kinds ; those made in one piece, mono- 
lithic, and those cast in separate molds and put into place. 

The risers on all steps and stairs should not be less than 6 in. nor 
more 'than 8 in., while the tread should be from 9 to 12 in., except 
where it is intended that more than one step should be taken on the 
tread, in which case 30 in. should be the minimum width. 

Foundations for all steps out-of-doors should extend below frost 
line or have a porous base with a drain situated at the lowest point 
to allow the water to run off. Steps should be wider than the walk 
or opening from which they lead, to avoid looking cramped, and in 
order to secure an artistic effect, should have some sort of projection 
or molding at their upper edge, if possible. A slight slope or pitch 
is also desirable to allow the water to drain off. 

Use 1 part cement, 2 parts sand and 4 parts broken stone or gravel. 
Fill to within 1 in. of the top of the riser, and as soon as this concrete 
has stiffened slightly (which usually is within about one-half hour) 
fill the remainder with a mixture of 1 part sand and 2 parts cement. 
Allow this to harden about y* hour and trowel lightly. 

Early on the second day remove the form from the face of the riser 
and trowel very carefully. 

This plate also gives a section detail of the method of casting in- 
dividual steps. 

This step is 7 in. by 14 in. inside measurement and 1 in. projection. 
Fill to within 1 in. of the top with concrete, 1 part cement, 3 parts 
sand and 6 parts broken stone, tamped hard. As soon as this has stif- 
fened, but before it has set, remove the board "A" next to the face of 
the concrete, which should not be fastened to the form, but simply set 
in and well greased. 

This will leave a space on the side and top of the step, also a small 
mold for the projection at the top of the step. Fill this with wet mor- 
tar, 1 part cement and l J / 2 parts coarse sand, and let it set. The forms 
may be removed and used again. Rub down the face of the riser with 
a brick or carborundum at the end of 24 hours. 

Reinforce all steps cast separately by iron rods placed about 1 in. 
above the bottom of the slab. 



68 




CONCRETE WALKS 



69 



Patent safety treads, of which there are many kinds on the market, 
are inserted as shown in the sketch when the mortar is still soft. This 
is not done on cheaper classes of work. It adds to the looks of the 
steps, however, and to the life of the nosing of the step, preventing the 
edge from being' chipped off. 

Concrete Walks 

Plate 26 gives details and sketch of ordinary walk construction. 

The laying of sidewalks is a simple operation if ordinary care is 
taken and several thousand running feet of walk have been laid by the 
author's pupils during the past few years and not a foot has ever 
failed. 

St. Johnsbury, Vermont, is situated about 40 miles from the Cana- 
dian border and the temperature varies from the vicinity of 100° in the 
summer to as low as 50° below zero in the winter. A walk which will 
stand expansion and contraction resulting from this great climatic 
difference, proves itself a substantial proposition and shows that boys 
of the seventh and eighth grades, with proper instruction, in any cli- 
mate, can lay any type of concrete work which they desire and build 
for permanence. 

Before laying the concrete a foundation of porous material, such 
as cinders or screened gravel, must be placed to form a base through 
which moisture can quickly and easily drain. This sub-base should 
be placed with as much care as the laying of the walk itself. 




Illus. 11. Leveling Up Forms, Tamping the Undercoat, and Using the Jointer and Edger. 



70 



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CONCRETE WALKS 



71 




Illus. 12. A 140-ft. Drip Around a School. 



Foundations should generally be 6 in. to 12 in. deep, depending 
upon the climate and character of the soil. In sections where there 
is a porous soil and a mild climate, foundations are sometimes omitted 
entirely. If the soil is clayey, blind drains or coarse gravel or tile pipe 
should be laid at the lowest point in the excavation, to carry off any 
water that might accumulate in the porous material of the foundation. 

Walks are frequently ruined by water freezing in the foundations 
and heaving them out of position. 

Excavate to the sub-grade previously determined upon, 3 in. wider 
on each side than the proposed walk, and fill with broken stone, gravel 
or cinders to within 4 in. of the proposed finished surface, wetting well 
and tamping in layers, so that when complete it will be even and firm, 
but porous. Place 2 in. by 4 in. scantlings (preferably dressed on in- 
side and top edge and perfectly straight) on top of the cinder founda- 
tion, the proper distance apart to form the inner and outer edges of 
the walk. The outside, or curb strips, must be from 1 to 2 in. lower 
than the inner edge of t.he walk. This will give a slight pitch to the 
finished surface and allow the water tOTiin off. A good rule to follow 
is to allow y% in. slope to every foot width of walk. For wide walks 
lay off the space between the scantlings into equal sections not larger 
than 6 ft. square, put 2 in. by 4 in. scantlings crosswise and in the 
center, see Fig. A, Plate 27. This will make every alternate space 
shown in the figure by diagonal lines, the size desired. 



72 



ELEMENTARY CONCRETE CONSTRUCTION 



MATERIALS FOR 100 SQ. FT. OF CONCRETE. 



Bags of Cement to 100 Sq. Ft. of Concrete 


Bags of Cement to 100 Sq. Ft. of 


Mortar 


Surface 






Surface 




Thickness 
Inches 


Proportions 


Thickness 
Inches 


Proportions 


l:iy 2 :3 


1:2:4 


1:3:6 


1:1 


i :iy 2 


1:2 


3 


sy 2 


6% 


4% 


% 


3y 2 


2% 


2y 4 


4 


11 


8% 


6 


% 


5 


4 


3% 


5 


14 y 2 


11 


7% 


i 


7 


5y 4 


4y 2 


6 


16% 


i3y 4 


- 9% 


i% 


sy 4 


7 


5% 


8 


22% 


18 


12 


iy 2 


10 


8 


6% 


10 


28% 


2iy 2 


15% 


i% 


12 


oy 4 


7% 


12 


34% 


26 y 2 


18% 


2 


14 


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9 



SURFACES LAID WITH ONE BARREL OF CEMENT. 



No. of Sq. Ft. of Concrete (Base) Laid 
with 4 Bags (1 Bbl.) of Cement 



Thickness 
Inches 



Proportions 



l:iy 2 :3 



1:2:4 



60 
46 
36 
30 
22 
19 
15 



No. of Sq. Ft. of Mortar Surface Laid 
with 4 Bags (1 Bbl.) of Cement 



Thickness 
Inches 



y 2 
% 
i 

iy 4 
i% 
i% 

2 



Proportions 



1:1 



114 
80 
57 
48 
40 
33 
29 



1 :1% 


1:2 


146 


178 


100 


114 


73 


89 


60 


70 


50 


59 


43 


52 


36 


44 



NOTE, — Four bags of cement equal 1 barrel. 

For proportions l:iy 2 :3 use for every 33 bags of cement 1 lar^e double load of sand and 2 
of gravel. 

For proportions 1 :2 :4 use for every 23 bags of cement 1 large double load of sand and 2 of 
gravel. 

For proportions 1 :3 :6 use for every 15 bags of cement 1 large double load of sand and 2 of 
gravel. 

One large double load contains 40 cubic feet or iy 2 cubic yards. 



Fill these spaces with con- 
crete to a depth of 3 in. (this 
depth should be 4 in. where 
there is more than ordinary 
traffic, or where the blocks are 
6 ft. square) 1 part cement, 2 
parts clean, sharp sand, and 4 
to 5 parts broken stone or 
screened gravel, then tamp 
until water begins to show r on 
top. On the same day, as soon 
as the concrete has set, remove 
crosswise and center scantlings, 
place a sheet of tar paper or a 
greased clapboard on the edges 
to separate them from all other 
squares and fill in the spaces 
thus left with 3 in. concrete as 
before. Mark the scantling to 
show where the joint came. 







Illus. 13. Walk Laid by Eighth Grade Boys. 



CONCRETE WALKS 



73 



The finishing coat should be 1 in. thick, of 1 part cement and \y 2 
parts clean, coarse sand or crushed stone screenings. This coat should 
be spread on before the concrete undercoat has taken its set, and 
smoothed off with a screed or straight edge (Plate 26) run over the 
2x4 scantlings, the object being to thoroughly bind the finishing coat 
to the concrete base. If this bond is imperfect, the walk will give a 
hollow sound under the feet, and is liable to crack after having been 
down one or two years. Smooth with a wooden float, or trowel and 
groove with the groover exactly over the joints between the concrete 
(Fig. A), Plate 27, so as to bevel the edges of all blocks. Do not trowel 
the finishing coat too much, not until it has begun to stiffen as the 
steel in the trowel tends to separate the cement from the sand, pro- 
ducing hair cracks on the surface and giving a poor wearing surface 
beside weakening the job. 

Plate 26 shows a popular type of groover. This is run alongside 
of a straight edge to insure a perfect joint. 

The edger is used to give a slight curve on all outside edges of fin- 
ished work. The finishing trowel is of steel and is used for surfacing 
completed work. An ordinary mason's trowel is also used for this 
purpose. The scratcher is used to roughen work to which a new sur- 
face of concrete is to be applied. It assists in securing a good bond 
and the one shown is made from a piece of old saw blade. 




Illus. 14. Entire Basement Floor of This School and Walk 10 ft. by 90 ft. Laid by 

Eighth Grade Boys. 



74 



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TWO-COURSE CURB AND GUTTER 75 

Keep the finished walks protected from dirt, currents of air, rain 
and hot sun during the process of setting, and further protect from the 
sun and traffic for 3 or 4 days, and keep moist by sprinkling daily. 
The covering may be sand, straw, sawdust, boards or building paper. 

Most walks are made with the single block width and this is nat- 
urally much easier than walks of two blocks width. Plan on leaving 
the job either at the noon hour or the end of the day, at the end of a 
block, so that the work may be resumed against a joint edge. 

- Two Course Curb and Gutter 

The foundations for curbs and gutters (Plates 26 and 28), like side- 
walks, should be governed by the soil and climate. 

Concrete curbing should be built in advance of the walk, in sec- 
tional pieces, 6 ft. to 8 ft. in length, and separated from each other and 
from the walk by tar paper or a cut joint, in the same manner as the 
walk is divided into blocks. 

Curbs should be 4 in. to 7 in. wide at the top, and 5 in. to 8 in. at 
the bottom, with a face 6 in. to 7 in. above the gutter. The curb should 
stand on a concrete base 5 in. to 8 in. thick, which in turn should have 
a sub-base of porous material at least 12 in. thick. The gutter should 
be 16 in. to 20 in. broad, and 6 in. to 9 in. thick and should also have 
a porous foundation at least 12 in. thick. 

Keeping the above dimensions in mind, excavate a trench the com- 
bined width of the gutter and curb and put in a sub-base of porous 
material. On top of this place forms, as shown (Plate 26) and fill 
with a layer of concrete, 1 part cement, 3 parts clean, coarse sand and 
6 parts broken stone, thick enough to fill the forms to about 3 in. below 
the street level. As soon as this concrete is sufficiently set to with- 
stand pressure, place the forms for the curb and after carefully clean- 
ing the concrete between the forms and thoroughly wetting, fill with 
1 part cement, 2y 2 parts clean, coarse sand and 5 parts broken stone. 
When the curb has sufficiently set to withstand its own weight with- 
out bulging, remove the Y in. board shown (Plate 26), and with the 
aid of a trowel fill in the space between the concrete and the form with 
cement mortar, composed of 1 part cement and 1 part clean, coarse 
sand. 

The finishing coat at the top of the curb should be put on at the 
same time. Trowel thoroughly and smooth with a wooden float, re- 
moving face form the following day. Sprinkle often and protect from 
sun and traffic for a few davs. 



76 



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ONE COURSE CURB AND GUTTER 



77 



One Course Curb and Gutter 

Plate 23 shows forms and method of placing concrete for the one. 
course method of curb and gutter construction. 

Excavate to the required depth, draining the soil if necessary by 
excavating 8 in. more and filling in with gravel or cinders. Build forms 
for the entire height (Plate 28), unless the earth is so firm that they 
need only be built for the part above ground. 

Expansion joints should be provided about every 10 or 15 ft. in 
the length of the curb. This is done by placing a board at the end of 
the form against which the concrete is poured. This gives a square 
end. 

Against this end place a thin piece of steel or wood or a couple of 
thicknesses of tar paper when the next section of the curb is poured 
to leave a slight opening. 

This steel or wood should be removed, but the tar paper can be 
left in place. 

The mixture should be 1 part cement, 2 parts sand and 4 parts 
gravel or crushed stone with particles not larger than \y 2 in. 

For every 100 ft. length of curb such as shown in Fig. A, Plate 
28, using the above mixture, there will be needed 24 bags of cement, 
48 cu. ft. of sand, and 6 cu. ft. of gravel or crushed stone. 

For the same length of curb and gutter, made as in Fig. B, Plate 28, 
there will be needed 30 bags of cement, 60 cu. ft. of sand and 120 cu. ft. 
of gravel or crushed stone. 




Illus. 15. Large Slab of Concrete Built by Boys for Convenience of Coal Teams. 



78 



ELEMENTARY CONCRETE CONSTRUCTION 



The general tendency at the present time seems to be toward the 
one course method of curb and .gutter construction. It is easier and 
cheaper to handle and if due care is taken in tamping and spading the 
concrete and then removing the forms as soon as possible and trowel- 
ing the surface a good finish can be obtained. 

Feeding Floors for Hogs and Cattle 

There is more or less waste where feed is thrown carelessly on the 
ground for cattle. A concrete feeding- floor overcomes this and does 
away with a muddy, disagreeable appearing barn yard. Wooden floors 
absorb moisture and eventually decay. Concrete floors are free of 
cracks and seams, economize on feed and manure, are easily construct- 
ed and will save their cost in a couple of years. 

Arrang-e for a well drained, substantial foundation (see method of 
laying walks), and construct the floor 5 in. thick of 1 part cement, 2 
parts sand and 4 parts gravel or crushed stone. Lay in 6 ft. sections 
using 1 in. x 6 in. boards staked upright for the side forms. Allow a 
slope of J4 i n - to the foot toward one side. 

A curb may be built around the edge, 4 in. higher than the floor 
to prevent hogs and cattle shoving- off the feed. 







Illus. 16. Feeding Floor for Hogs. 

Extend the curb about 18 in. into the ground to prevent hogs from 
rooting under the floor. Make this curb about 5 in. thick. Plate 29 
shows the method of constructing the floor. 

Make the inside form for the curb of 2 in. x 4 in. plank held in posi- 
tion by overhanging cleats from the stakes of the outside forms (see 
Fig. B, Plate 28)/ 



WASHING FLOORS 



79 



Carriage and Automobile Washing Floors 
Plate 29 also shows drawings for a good type of washing floor. 
Build the floor large enough to take in the wheels and shafts of 

the wagon and also of a size to allow the person who does the washing 

freedom to work. The average size is about 12 ft. 

The concrete should be 5 in. thick and slope each way toward the 

center where a drain should be provided, as shown, otherwise the 

water will run off the sides taking with it the dirt from the vehicle. 




Illus. 17. Carriage and Automobile Washing Floor. 

Construct the drain by excavating, directly in the center of the 
floor, a hole large enough to contain a good-sized barrel which has 
the bottom removed. Fill this barrel with stones and, if necessary, 
run a drain from the barrel to some convenient point. 

The concrete should be made up of 1 part cement, 2 parts sand 
and 4 parts crushed stone or gravel. Finish with a wooden float. 

A floor of this size will require 13 bags of cement, 26 cu. ft. of sand 
and 52 cu. ft. of gravel or crushed stone. Protect the same as for 
walks.. 

*A Concrete Manure Pit 

The soluble part of manure is the most valuable and a concrete pit 
preserves the full strength of the manure. 



80 



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MANURE PIT 



81 



According to government reports one load of manure from a con- 
crete pit is worth from \ l / 2 to 2 loads of manure as commonly stored 
against the side of a barn. 

The excavation should be about 2 l / 2 ft. deep, allowing for a 6 in. 
floor at the same time bringing the walls above ground. 

Slope toward the end where the drain is to be situated, making one 
end about 6 in. lower than the other. 




Illus. 18. Manure Pit. 



For firm ground there is only need of outside forms above ground. 
Have the inside form slope slightly, as shown in Plate 30, making the 
top of the wall 6 in. wide and the bottom 10 in. wide. Make the gutter 
shape with a template shortly after the concrete has been poured. Re- 
inforce with wire mesh as shown in drawing. See Plate 33 for method 
of making forms. 

A mixture of 1 part cement, 2 parts sand and 4 parts gravel or 
crushed stone should be used and for a pit the size of the one given 
there are needed 93 bags of cement, 186 cu. ft. of sand and 372 cu. ft. 
of gravel or crushed stone. 

A manure pit may be roofed over, which will assist in eliminating 
the fly nuisance. 



82 



ELEMENTARY CONCRETE CONSTRUCTION 



Concrete Duck Pond or Wading Pool 

A duck pond for the poultry raiser or a wading pool for the children 
may be made in a similar way to the manure pit. 

The dimensions for a fair-sized duck pond would be 8 ft. wide, 12 
ft. long and 6 in. for the thickness of the walls and the bottom. 

Using a 1-2-4 mixture, with walls 18 in. deep on the outside, there 
will be needed 20 bags of cement, 40 cu. ft. of sand and 80 cu. ft. of 
gravel or crushed stone. 




Illus. 19. Concrete Duck Pond. 



Hot Beds and Cold Frames 

Plate 31 gives a drawing for a suggested type of cold frame. 

Excavations should be made below frost line and make forms for 
a 4 in. wall. 

It is a good plan, if old window frames are available, to construct 
the forms to fit the window frames at hand. 

The hot bed should have a slope as shown in the drawing and 
should be located so as to face the south or southeast. 

Use a mixture of 1 part cement, 2y 2 parts sand and 4 parts gravel 
or broken stone. Remove the forms in 2 or 3 days and keep damp for 
a couple of weeks. 



83 




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FOUNDATIONS 85 

Laying Out Foundations 

Buildings are usually located with reference to some existing ob- 
ject, such as a highway, a drive or some other building. 

When the location depends upon some other object the first line 
to be determined should be the one influenced by the location of that 
object. With this established, it may be used as a base line, and the 
corners which come on it should be located next. In case the building 
is not located with reference to some other object, the base line should 
be chosen arbitrarily, and the corners and other lines laid out from it. 

One corner will probably be located with reference to some other 
object, and the other corner on the base line will be located a distance 
from the first equal to the length or breadth of the building. Mark 
these by stakes driven in the ground, the exact point being indicated 
by a nail driven in the stake. 

Plate 32, Fig. A, gives a drawing of the method of laying out a sim- 
ple foundation and the above mentioned points are indicated by A and 
B, AB being the base line. 

After the corners on the base have been definitely located, proceed 
to locate another corner marked C. The line which runs from A to C, 
perpendicular to the base line must first be located. 

To obtain a true right angle at A, measure accurately 6 ft. from A, 
along the base line toward B, and mark by a stake and nail, as shown 
at Y. Xext measure out exactly 8 ft. from A on the direction of the 
corner to be found, and mark a curved line on the ground ; measure 
from Y 10 ft. to a point on the curved line ; drive a stake at this point 
and check the measurement. Mark the location accurately with a 
nail on the stake. This point is marked Z in Fig. A, Plate 32. The 
point C will lie on the line AZ projected. Corner D can be located 
from B in a similar manner. 

Fig. B, Plate 32, shows the method of locating construction lines, 
after the corners have been located. These lines remain permanent 
during the construction of the foundation. 

The fence-like forms shown in Fig. B, should be located at least 
8 ft. from the foundation lines and should be long enough to permit of 
marking both the inside and outside foundation lines on the top or 
horizontal boards. Brace the frames enough to withstand the pressure 
of the tightly drawn cords, which they must support as nearly hori- 
zontal as possible. 

Locate the points on the corner boards by drawing a cord from 
one board to the other, bringing it directly over the nails at the two 
corners on the same line ; these points should be accurately marked 
on the board by a notch, or by cutting a shallow groove with a saw. 






1 
I 




SIMPLE FOUNDATIONS 87 

This cord represents the outside line of the foundation ; the inside 
line will be indicated by measuring in a distance equal to the thickness 
of the proposed foundation and stretching a cord between these two 
points. Carefully mark these points on the board in some way differ- 
ent from the marks showing outside lines. 

A plumb-bob suspended from these lines to the ground will indicate 
the line of excavation. 

Simple Foundations 

A form made like Fig. A, Plate 33, measuring 10 or 12 in. on each 
side at the top and a little more at the bottom, being sloped so that it 
may be lifted easily off the concrete, is a very useful form to make and 
keep around. Piers for the foundation of small buildings are easily 
made with this type of form. The top level of the form can be reg- 
ulated by putting blocks under the handles of the form. 

The hole for the base of the pier should be 6 or 8 in. bigger each 
way than the form, thus allowing the concrete to spread as shown. 

Forms for taller piers should be very strongly braced all around 
each side by pieces of 2 in. x 4 in. material spiked together and spaced 
about 18 in. apart. 

Columns over 6 ft. in height should have yokes of 4 in. x 4 in. 
material, held together by bolts and side pieces held in position by 
wedges. These should be spaced about 20 in. apart. These columns 
should be reinforced with % in. iron rods. 

A column which is to carry no great weight, may have the forms 
removed inside of 48 hours. 

Fig. B, Plate 33, shows a simple box form for column footings. 
The drawing is self-explanatory. 

Fig. C, Plate 33, shows form and method of casting a concrete 
foundation for a gasoline engine. The foundation consists of a block 
of concrete resting on a firm sub-base, with anchor bolts properly set, 
by means of which the engine is held in place. Concerns manufactur- 
ing engines usually state the length of anchor bolts, the location in 
regard to each other, and the size of the foundations needed for the 
various sizes of machines. 






$ : ^ * * 

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VARIOUS TYPES OF FOUNDATIONS 89 

Various Types of Foundations 

Plate 34 shows three different types of foundations. 

Sometimes because of the nature of the soil, or possibly because 
a team and scraper are used in removing the earth, the walls of the 
excavation cannot be kept perpendicular. 

In such cases forms must be placed for that portion of the founda- 
tion below ground as well as for the portion above, if there be any. 

Unless forms for the whole foundation are to be put up at one time, 
it will be best to build them flat on the ground, in units of convenient 
length, and then erect them in place. By having the forms constructed 
in this way they may be removed and used again, with the minimum 
amount of damage to the lumber. In building forms flat the stringers 
should be carefully leveled and the uprights and sheathing carefully 
placed in their correct relative positions, otherwise the forms will be 
askew when erected. 

If the forms are to be built in position, first place the stringers 
shown at the bottom of the inner form (Fig. A), so that when the up- 
right 2x4's and the sheathing are in place, the inside face of the sheath- 
ing will be in line with the inner face of the proposed wall. Nail the 
lower end of the uprights to the stringer and attach the top board of 
the sheathing to hold the vertical 2x4's the proper distance apart. 

The frame must now be plumbed carefully and held in place by 
the braces extending between the upper end of the 2x4's and stakes 
driven in the ground. The remaining sheathing boards may then be 
placed, starting at the bottom. 

With so much of the inner form set, the outer form can easily be 
placed and fastened to the inner cne, as shown in the sketch. 

On account of the small place in which to work, the outer part of 
the form can more easily be built in sections, as described, and lowered 
into position. When the forms are not to be handled in sections, it 
will be advisable to ''break joints" in placing the sheathing", for by so 
doing the form will be somewhat stiffer and the alignment be more 
easily maintained. In erecting forms one must bear in mind that they 
are to be removed, and when there is only a narrow space between the 
forms and the earth wall, provision should be made for their removal 
by a means that will be of least damage to the lumber. 

Instead of supporting the outer part of the form by independent 
bracing into the earth, it will be better to wire it to the inside section. 
Spacing blocks of a length equal to the thickness of the walls should 
be inserted to keep the two sections of the form in their relative posi- 
tions. The wires are then twisted with a piece of iron or a large spike, 
until the outer section is drawn tightly against the spacing- block. 



90 



ELEMENTARY CONCRETE CONSTRUCTION 



The top of the two sections are held together by cleats, as shown. 
If the wall is very high it may be necessary to place additional wires 
near the center of the uprights. 

Some means must be provided for removing the spacing blocks as 
the concreting progresses. This can be done by attaching a wire to 
the block by which it can be withdrawn after being knocked loose. 

Figure B shows a type of form used when the character of the soil 
permits of placing concrete directly against the earth, doing away with 
the outer form below the ground level. When depositing concrete in 
this type of form, care must be exercised, as dirt is likely to be knocked 
off the sides of the bank into the concrete. The edge of the excavation 
should be protected with boards. 

If a smooth, face is desired, dressed lumber should be used. 

Figure C shows a type.' of form for use on a sub-base of concrete 
the finished part being entirely above ground. 

The form shown can be constructed in sections or built in place, 
depending somewhat on local conditions. If the inner and outer parts 
of the form are built separately in sections, they may be leveled care- 
fully and plumbed as units, while if built in position, care must be 
taken in placing each timber. In all cases the bottom boards of the 
sheathing should be flush with or a little below the top edge of the 
trench. The top boards should be the height of the finished wall. 

It will be seen from the sketch that the forms are suspended over 
the trench and not allowed to rest on the sub-base. This is accom- 
plished by placing stringers on the ground a short distance back from 
the trench, supporting the triangular frame bracing. 




Illus. 20. Hot Bed Laid by These Boys. 



RETAINING WALL 



91 



Retaining Wall 

The design for a retaining wall shown on Plate 35 is what is known 
as the gravity section, which means that the earth pressure is resisted 
by the weight of the wall. The following table gives the necessary 
dimensions and amount of material per foot of length of wall, assum- 
ing the concrete is made of 1 part cement, 2y 2 parts of sand and 5 parts 
of gravel or crushed stone. 

DIMENSIONS OF RETAINING WALLS AND QUANTITY OF MATERIALS 

FOR DIFFERENT HEIGHTS OF WALL. 

Proportions: 1 Part Portland Cement to 2% Parts Sand to 5 Parts Gravel or Stone. 



Height 










Amount of Materials per One Ft. 


of Wall 
Above 


Total 
Height 


Thickness 


Thickness 


Thickness 
at 


Length of Wall 










Ground 


of Wall 


Base 


Ground 


Top 






Gravel or 


H ' 




B 
Ft. In. 


Level 


A 


Cement 


Sand 


Stone 


Feet 


Feet 


Ft. In. 


Inches 


Bags 


Cu. Ft. 


Cu. Ft. 


2 


6 


2 2 


1 6 


10 


1% 


4% 


9 


3 


7 


2 5 


i 7y a 


10 


2y 2 . 


-5y 2 


11 


4 


8 


2 9 


i n 


12 


3 


7 


14 


5 


9 


3 2 


2 1 


12 


3% 


9 


19 


6 


10 


3 6 


2 4y 2 


15 


4% 


ny 2 


23 


7 


11 


3 10 


2 8 


18 


6 


14 


28 


8 


12 


4 2 


2 10 


18 


7 


i6 y 2 


33 



Note: 



-A large single load of sand or gravel is about 20 cubic feet. 
A large double load of sand or gravel is about 40 cubic feet. 



The exposed side or face of the retaining wall may be finished as 
described under chapter for finishing. The top surface must not be 
plastered or it will crack and is apt to peel off. The surface should be 
smoothed off with a trowel when the concrete is first laid, then as soon 
as it has begun to stiffen, scrape off any light-colored scum with a wire 
brush or old curry comb, wet slightly and trowel it, preferably with a 
wood float, but using no fresh mortar. 



Design for Small Dam 

The second sketch on Plate 35 shows a suitable design for a small 
dam. 

If a dam is to be built more than 4 or 5 ft. above the bed of the 
stream, an engineer should be called upon to design it and look after 
the construction. 

For an ice pond or pond for watering stock a concrete dam may 
be built across a brook without difficulty. 

If possible, dig a temporary trench so as to carry the water around 
the dam while it is being built. If this cannot be done, run the water 
through a wooden trough in the middle of the dam, and after the wall 
on each side of it is finished carry the forms across the opening, and 
make it tight enough so that the water is quiet between them ; then 
place the concrete in pails, placing a board over the top of the pail, 
and lowering it carefully to the bottom. Turn the pail upside down, 



92 






1 



i 

SI 

I 





§ 



DESIGN FOR SMALL DAM 



93 



carefully remove the board and slowly raise the pail, allowing the 
concrete to flow out. Great care must be used not to disturb the water 
in which the concrete is being- placed nor to touch the green concrete. 
Concrete must never be placed under water if there is any current, 
on account of the cement being washed away, leaving only the sand, 
and stone. 

Another method of placing concrete under water is to pass the 
concrete slowly through a spout or tube which reaches to within a 
couple of inches of the bottom when the concrete is to be placed. The 
tube must be kept full and the concrete kept moving continuously and 
slowly through it. On large w r ork specially designed buckets are used 
for depositing the concrete under water, but these are generally op- 
erated by a derrick. 

Dig a trench across the stream slightly wider than the width of 
the base of the dam, carrying it down about 18 in. or 2 ft. below the 
bed of the brook, or, if the ground is soft, deep enough to reach good 
solid bottom. In case the earth is firm enough for a foundation, but is 
porous either under the dam or each side of it, sheet piling, consisting 
of 2 in. tongued and grooved plank, can be pointed and driven with a 
heavy wooden mallet so as to prevent water flowing under or around 
the dam. Build the forms so as to make the wall of the dimensions 
shown in the table. Wet them thoroughly, then mix and place the 
concrete very carefully, using- 1 part cement, 2 parts clean, coarse sand 
to 4 parts screened gravel or broken stone. 

DIMENSIONS FOR SMALL DAMS AND QUANTITY OF MATERIALS FOR 

DIFFERENT HEIGHTS OF DAMS. 

Proportions : 1 Part Portland Cement to 2 Parts Sand to 4 Parts Gravel or Stone. 



Height 


Depth 

Below 

Bed of 

Stream* 


Thickness 
at Base 


Thickness 
at Top 


Amount of Materials per Foot 
of Length of Dam 


Bed of 
Stream 


Cement 


Sand 


Gravel or 
Stone 




Feet 
G 


Feet 
B 


Feet 
T 


H 


Bags 


Cu. Ft. 


Cu. Ft. 


1 
2 
3 
4 
5 
6 


1% 
1% 

1%. 

2 
2 
2 


1 
1 
2 
2 

2y 2 

3 


1 
1 

iy 2 
i% 
i% 


V-2 
1 
1% 

2% 
3% 

4y 2 


% 

IY2 

4 

5 

6% 

8% 


iy 2 

3 

8 
10 
13% 

17 y 2 



*Make deeper if necessary to get a good foundation. 

A wet mix will help make the concrete water tight, and if possible 
lay the entire dam in one day, not allowing one layer to set before the 
next one is placed. 

If it is necessary to lay the concrete on two consecutive days, scrape 
off the top surface of the old concrete in the morning, thoroughly soak 



so 



fc 

X 

^ 




DESIGN FOR CONCRETE FOUNDATION 



95 



it with water and spread on a layer about J4 m - thick of pure cement 
of the consistency of thick cream, then place the fresh concrete before 
this cement has begun to stiffen. 

If the forms on the lower side of the dam are well braced, the forms 
on the upstream side may be removed in 3 or 4 days, and the pond 
allowed to fill. The forms on the down-stream face should be left in 
place, well braced for 2 or 3 weeks. No finish need be given to the 
surface. 




Illus. 21. Model Bridge with Concrete Abutments. 

Design for Concrete Fountain 

The design for a small fountain, shown on Plate 36, is simple in 
construction and not expensive to make. 

There must first be a pipe laid to what will be the center of the 
fountain and it must connect with the regular water supply. 

A circular excavation must first be made, 12 to 18 in. deep, to bring 
the water supply pipe up to the decided water line, usually at the 
height of the ground. A nozzle should be attached to this, to regulate 
the spray. 

A drain pipe should be located even with the floor of the basin and 
an overflow pipe placed on the wall, a trifle below the height of the 
feed pipe, which runs into the drain outside the fountain wall, as 
shown in the drawing. 

The bottom of the basin, around the piping, must be well tamped 
and covered with about 4 in. of cinders, which also require generous 
tamping, wetting them down well. 

A concrete consisting of 1 part cement, 2 parts of good, clean sand 
and 4 parts of gravel or broken stone, should be mixed and deposited 
with care. 

Protect the fresh concrete for several days, wetting each day to 
insure drying out evenly. 



96 







CONCRETE BIRD BATH 
Concrete Bird Bath 



97 



Plate 37 gives a simple design for a concrete bird bath, with 
sketches showing the various steps in molding and sweeping the 
concrete. 

A strong, substantial table may be utilized for this work or it may 
be done on a plank platform of wood. See Fig. C. 

A r /4 in. dowel should be attached to the table, letting the end pro- 
ject through to the underside and held firmly in place. It should be 
of sufficient height to allow the sweeps to be slipped on, as is shown 
in the sketches on Plate 37. A wooden sweep should be shaped to the 
required size for forming the inside of the top, Fig A, Plate 37. Place 
sufficient moist clay on the board and sweep as shown in Fig. A. 

The form for the sweep, shown in Fig. B, which is the underside 
of the top, must be made of fairly stiff sheet metal, securely attached 
to the wooden frame, as indicated. Mix enough concrete, using a wet 
mixture, to buijd up the required thickness. This is placed on top of 
the clay mold previously made, and oiled and the metal template placed 
on the spindle. Sweep until the surface is smooth. 

The base is swept as in Fig. C. 




Illus. 22. Using the Sweep on a Plaster of Paris Illus. 23. Completed Top of Bird Bath and 
Form Preparatory to Casting the Top the Shaft. 

of a Bird Bath. 



98 



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5 




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SINGLE CONCRETE GARAGE 99 

Pieces of fine mesh wire should be placed inside the concrete to 
stiffen it. Keep wet until thoroughly dry, which should be in two or 
three days. It will be noticed in the sectional view that the various 
parts are joined by means of a }i in. rod or dowel. When putting the 
bird bath together, a small amount of "neat cement," which is cement 
with enough water added to make a paste, is applied at all joints. 

Another method of sweeping the molds is to mix up just enough 
plaster of Paris to place under the sweep and sweep this very quickly 
with the template. The plaster sets quickly and the work must be 
done without loss of time. After the core is hard it should be sand- 
papered and shellac applied to the surface. 

Oil the core and cover it with the concrete, packing it down firmly, 
and building up to the required thickness. 

Place the template for sweeping out the inner or bowl part of the 
top, and sweep to the desired smoothness. 

This problem is not only interesting to construct, but is a valuable 
addition to any lawn or garden and at the same time attracts and 
benefits the birds. 

Single Concrete Garage 

The design of a garage is generally influenced by the architectural 
treatment of the house and neighboring buildings. 

The logical location for the garage is at the rear of the house, but 
this point must be settled to suit local conditions, the main idea being 
the convenience and accessibility from the street. 

Plate 38 gives a good type of concrete garage, but very few dimen- 
sions are given, as the size depends on the car to be housed and the 
amount of room available. 

It is well to plan ahead for the possibility of two automobiles, or 
space fcr a visiting car, or perhaps the letting of one-half of the garage. 

It is very necessary that the garage be as near fireproof as possible. 
Insurance companies allow lower rates on concrete constructed build- 
ings. This type of garage is simple to construct, its upkeep is cheap, 
it is permanent and needs no painting or repairing, is clean and easy 
to keep clean. 

The method of constructing forms and floors is shown on previous 
plates. The floor should have a slight pitch to a drain in the center 
(see Plate 29), and the material required for the entire building is 
given on the drawing. 

This garage shows a shingled roof, but a concrete roof may be con- 
structed instead, of a low arch type, the supporting forms being con- 
structed on the inside of the srarasre. 




A Class of Boys in "Elementary Concrete Work" Starting Out for a Job. 



INDEX 



Aggregates, 10 

Cinders, 13 

Coarse — gravel, 11 

Fine — sand, 11 
Anchor weight, 34, 35 

Bird bath, 96, 97 

Brick, 32, 33 

Brush surfaces, 23 

Burning cement to incipient fusion, 9 

Carriage and automobile washing 

floors, 76, 79 
Cement, classes of, 8 

Commercial, and its storage, 9 

Composition of, 7 

Drying and grinding, 8 

History of, 7 

Portland, manufacture of, 8 

Proportioning and mixing, 9 

Quarrying, 8 

True use of word, 21 
Cinders as aggregate, 13 
Circular watering trough, 61, 64 
Classes of cement, 8 
Coarse aggregate — gravel, 11 
Cold frames and hot beds, 82, 83 
Colored surfaces, 24 
Commercial cement and its storage, 9 
Composition of cement, 7 
Concrete, forms for, 21 

Mixture, 28 

Protection of, 21 

Surface designs, 25 

Use of in winter, 26 

Waterproofing, 25 
Corner reinforcing, 100, 101 
Curb and gutter, one course, 74, 77 

Two course, 68, 74, 75 

Dam, design for small, 91, 92 
Design for concrete fountain, 94, 95 

Small dam, 91, 92 

Concrete surfaces, 25 
Details of wall and window construc- 
tion, 100, 101 
Dish for bulbs, 42, 43 
Dressed surfaces, 24 
Drying and grinding, 8 
Duck pond or wading pool, 82 

Elementary concrete work, equipment 
used in, 15, 16 

Equipment used in elementary con- 
crete work, 15, 16 

Estimating, 26 

Feeding floors for hogs and cattle, 76, 

78 
Fence posts, 48, 49 
Fine aggregate — sand, 11 
Finish, mortar, 22 
Finishes for concrete, various, 22 



Floors, carriage and automobile wash- 
ing, 76, 79 

Feeding, for hogs and cattle, 76, 78 
Flower boxes, 43-45 
Forms for concrete, 21 
Forms, length of time to be left in 

place, 21 
Foundations, laying out, 84, 85 

Simple, 86, 87 

Various types of, 88, 89 
Fountain, design for, 94, 95 

Garage, single, 98, 99 
Garden bench, 57-59 
Grinding the clinker and adding gyp- 
sum, 9 

History of cement, 7 

Hitching post, 46, 47 

Horse block, 40, 41 

Hot beds and cold frames, 82, 83 

Lawn pedestals, 54-56 

Laying out foundations, 84, 85 

Length of time forms should be left 

in place, 21 
Loam, tests for, 11 

Manufacture of Portland Cement, 8 
Manure pit, 79, 80 

Materials needed, table for determin- 
ing quantities, 27 
Measuring box, quantity of materials 

and sizes, 17, 18 
Method of washing sand, 11 
Miscellaneous problems, 36, 37 
Mixing, 17-20 
Mixture, concrete, 28 

Mortar, 28 

Various, for various purposes, 15 
Mortar, colored, table, 25 

Finish, 22 

Mixture, 28 

One course curb and gutter, 74, 77 

Problems : 

Anchor weight, 34, 35 

Bird bath, 96, 97 

Brick, 32, 33 

Carriage and automobile washing 

floors, 76, 79 
Corner reinforcing, 100, 101 
Design for fountain, 94, 95 
Design for small dam, 91, 92 
Details of wall and window con- 
struction, 100, 101 
Dish for bulbs, 42, 43 
Duck pond or wading pool, 82 
Feeding floors for hogs and cattle, 

76, 78 
Fence posts, 48, 49 
Flower boxes, 43, 45 
Garden bench, 57-59 



INDEX— Concluded 



Hitching post, 46, 47 

Horse block, 40, 41 

Hot beds and cold frames, 82, 83 

Lawn pedestals, 54-56 

Laying out foundations, 84, 85 

Manure pit, 79, 80 

Miscellaneous, 36, 37 

One course curb and gutter, 74, 77 

Retaining wall, 91, 92 

Roller, 38, 39 

Sand box, 52, 53 

Simple foundations, 86, 87 

Single garage, 98, 99 

Steps and porch construction, 66, 61 

Sun-dials, 54-56 

Supports for parallel bars, 50, 51 

Troughs, 57-60 

Two course curb and gutter, 68, 74 

Various types of foundations, 88, 89 

Walks, 68-75 

Wall reinforcing, 100, 101 

Waste water receptacle, 64, 65 

Watering trough, circular, 61, 64; 

small, 61, 63 
Window and door openings, 100, 101 

Proportioning materials, 13 
Proportioning and mixing cement, 9 
Protection of concrete, 21 

Quantity of materials and sizes of 

measuring box, 17, 18 
Quarrying, 8 
Questions and answers, 29, 30 

Reinforcing, 19 

Corners, 100, 101 

Walls, 100, 101 
Retaining wall, 91, 92 
Rocks, value of different, 10 
Roller, 38, 39 
Rubbed surfaces, 23 

Sand box, 52, 53 

Method of washing, 11 
Washer, 12 



Setting of sun-dial, 57 
Sidewalk construction, 68-73 
Simple foundations, 86, 87 
Single concrete garage, 98, 99 
Small watering trough, 61-63 
Steps and porch construction, 66, 67 
Storage of commercial cement, 9 
Sun-dials, 54-56 

Setting of, 57 
Supports for parallel bars, 50, 51 
Surfaces, brush, 23 

Colored, 24 

Dressed, 24 

Rubbed, 23 

Table for colored mortar, 25 

For determining quantities of mate- 
rials needed, 27 

Tests for loam, 11 

Troughs, concrete, 57, 60 
Circular, 61, 64 
Small watering, 61-63 

True use of word cement, 21 

Two course curb and gutter, 68, 74 

Use of concrete in winter, 26 

Value of different rocks, 10 
Various finishes for concrete, 22 
Mixtures for various purposes, 15 
Types of foundations, 88, 89 

Walks, 68-75 

Wall reinforcing, 100, 101 

Retaining, 91, 92 
Wall and window construction, details 

of, 100, 101 
Waste water receptacle, 64, 65 
Water for mixing, 13 
Watering trough, circular, 61, 64 

Small, 61-63 
Waterproofing concrete, 25 
Window and door openings, 100, 101 



.'llllllltlllllM T ! 1 1 1 1 1 1 > 1 1 1 1 1 1 1 1 1 1 1 1 1 




Boy 

Bird House Architecture 

By LEON H. BAXTER 

St. Johnsbury, Vt. 

A most complete and specific school 
manual and guide on the making, 
finishing and setting of bird houses. 
Every phase of construction from the 
laying out of the lumber, to the fin- 
ishing, painting and setting up, is 
covered in a most simple and thor- 
ough manner. Each design offered is 
of a proven house, one that has 
served as a home for some of our 
songsters. Illustrated with photo- 
graphs and working drawings. 



Cloth, 64 pages— Price, $1.00, net 



The Bruce Publishing Company 

MILWAUKEE, WIS. 



" iNiniitiiiiiiiiiimm nil in ii i :iiii in tint :mi iiiiiiiimiin in nimiii milium iimiiiimmmiimiHiiimimmmii minimi," 



